sybase dba user guide for beginners

SYbase DBA

Sybase DBA Manual

Sybase DBA

11/10/2010

It is a humble attempt from our end to welcome the readers into the intriguing and amazing world of SYBASE. Outmost care has been taken to ensure that it is easily grasped even by the novices. This document hopefully will become the first step before you launch yourself into the profession of DATABASE ADMINISTRATION. Few of the topics have been copied from www.sybase.com.

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Contents

What is DBMS/RDBMS? 4

Duties of DBA 4

ASE Overview and Architecture Diagram 4

What is Database? 5

How is data stored in database? 7

Disk Initialization 9

New Page Allocation Procedure in ASE 10

Segments 11

Thresholds 12

Roles & Groups 12

Logins & User 13

Interface & Error Log File 13

ASE Memory Usage 14

Db_options 16

Configuration Parameters 16

Indexes 17

Update Stats & Sp_recompile 20

Locks & Isolation Level 20

Phases When Query Is Executed & Process Status 22

Hit/Miss Diagram 24

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Start and Shut Down Of Server 26

Backup/Recovery/Refresh/Restore 26

Dbcc 27

MDA Tables 28

Multiple Temp Databases 29

Utilities 29

Troubleshooting 30

How to Apply EBF 31

Query and Server Performance Tuning 32

Calculations 33

Sybase Diagram 34

Replication Overview and Architecture Diagram 34

Crontab 37

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What is DBMS/RDBMS?A Data Base Management System is a collection of programs that enable users to create and maintain a database. It can also be said that DBMS is a process of managing data for efficient retrieval and storage of data. Hence it is general purpose software that facilitates the processes of defining, constructing, manipulating and sharing databases among various users.

The RDBMS is a database management system that that stores data in the form of tables and there is also a relationship that exists between the tables. In a RDBMS data and information is acquired by the relations or tables.

Duties of DBAThe following are some of the duties of a DBA-

Checking the server status (automate the job in crontab to monitor the server status). Ensure that backups happen daily. Health check for all the databases. Performance related tasks (automate Update statistics & sp_recompile in crontab). Rebooting the servers during maintenance window. Security Management (adding logins/users with proper approvals from application/technical

leads). Proactively monitoring the database data & log growth (threshold setup). Monitoring error logs.

ASE Overview and Architecture Diagram

Adaptive Server Enterprise (ASE) has long been noted for its reliability, low total cost of ownership and superior performance. With its latest version, ASE 15, it has been dramatically enhanced to deliver capabilities urgently needed by enterprises today. It lays the long-term foundation for strategic agility and continuing innovation in mission-critical environments. ASE 15 provides unique security options and a host of other new features that boost performance while reducing operational costs and risk. Find out how you can exploit new technologies such as grids and clusters, service-oriented architectures and real-time messaging.

ASE 15 meets the increasing demands of large databases and high transaction volumes, while providing a cost effective database management system. Its key features include on-disk encryption, smart partitions and new, patent-pending query processing technology that has demonstrated a significant increase in performance, as well as enhanced support for unstructured data management. ASE is a high-performance, mission-critical database management system that gives Sybase customers an operational advantage by lowering costs and risks.

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Uses the 2K pool for Roll forward / Rollback

User Databases

Data Server

Error log

Interface

Configuration File

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Master Device Initialized

<Servername>.krg

System Devices and DatabasesUser Devices

File System / Raw DevicesDB Options Segments / Thresholds

Pool

SHARED MEMORY

MAX MEMORY

ASE executables

PROCEDURE CACHE

USER LOG CACHE

DATA CACHE

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Default 2K pool

Wash Marker can range from 20% to 80 %

MRU LRU

POOL

Wash Area

Statement Cache

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Figure 1 Architecture Diagram

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What is Database?

Database is collection of data objects (Tables, Views, Stored Procedures, Functions, Triggers and indexes).

Number of databases that can be created under one adaptive server depends on the configuration parameter “number of databases”

All the information regarding databases created in single adaptive server can be viewed in system table SYSDATABASES and the database space usage in SYSUSAGES.

Databases are broadly divided into system and user databases.o System databases are default databases created during adaptive server installation

(master, model, tempdb & sysbsystemprocs) few system databases are optional and can be created/configured by DBA (sybsecurity, sybsyntax, DBCC and sybsystemdb). Some of them are Sybsecurity, sybsystemdb, pubs, sybsyntax, and dbcc.

o User databases can only be created by the system administrator or whoever has the system administrator privileges. A max of 256 Databases can be created on single adaptive server.

Syntax Create database database_name [On {default | database_device} [= size] [, database_device [= size]]...] [Log on database_device [= size] [, database_device [= size]]...][With {override | default_location = "pathname"}][For {load | proxy_update}]

Options:With override: must be specified when data and log segments are placed on a same Database device. For load: does not initialize the allocated space which saves times when a dump will be loaded next

Alter database db_name on data_dev2= '100M' Drop database db_name: drops the database which is not currently in use and not contain any

constraints referring to other databases. Dbcc dbrepair (db_name, dropdb) Sp_helpdb: displays information about specified database. When used without any db name

displays information about all databases. When db name is current database then displays even segment information.

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Sp_helpdb db_name, 'device_name' displays device fragments in alphabetical order; default order in which device fragments are added

sp_spaceused: Displays total space used by all the tables in current databasesp_spaceused appl3

sp_renamedb olddb_name, new_dbname (db must be in single user mode)

Master DB stores information regarding all other databases, Logins, Devices, etc. It keeps track of all the databases. It has nearly 32 system tables. Some of them are syslogins, sysdb, sysdevices, sysroles, sysprocess, etc. Server wide details are stored in here. It’s the heart of the Server.

Model DB is the template for all the databases, excluding the Master. Temp DB can be referred as a workspace for the users to perform operations. It’s a volatile

memory, so whenever the server is rebooted, it has to be recreated using the template from Model DB. Three kinds of table are created in the Tempdb,

o Session level (table name prefixed with #) - A session level temporary table exists till the expiry of the session of the user

o Global level (table name prefixed with tempdb) - A global level temporary tables exists till the server is rebooted

o Workable tables- System creates this kind of tables like for sorting purpose.

SYBSYSTEMPROCS DB stores all the system procedures

How is data stored in database? The data in database is stored in the form of tables. The smallest unit of data storage is Page. 8 contiguous pages is an Extent. The size of a page can

be 2KB, 4KB, or 16KB. Table size = 1 Extent * page size. Allocation unit: - Collection of 256 pages is called an Allocation Unit. Each Allocation unit has a

first page called Allocation Page, which stores all the information of the pages of the Unit. Object Allocation Map stores about the information of the pages of the Table. In return all the

OAM point to the AP of the entire allocation unit where object data is stored. The number of entries per OAM page also depends on the logical page size the server is using.

The following table describes the number of OAM entries for each logical page size:

2K logical page size 4K logical page size 8K logical page size 16K logical page size250 506 1018 2042

Global Allocation Map (SYSGAMS system table) records and tracks all the information of all the AU’s in the particular database. SYSGAMS is not accessible by any user. For every 8GB of disk space a new GAM is created.

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Figure 2 Overview on Allocation Unit

Latch: - Latches are non transactional synchronization mechanisms used to guarantee the physical consistency of a page. While rows are being inserted, updated or deleted, only one Adaptive Server process can have access to the page at the same time. Latches are used for datapages and datarows locking but not for all pages locking.

Note: - The most important distinction between a lock and a latch is the duration

Table 1 Difference between Latch and Lock

Latch LockA latch is held only for the time required to insert or move a few bytes on a data page, to copy pointers, columns or rows, or to acquire a latch on another index page

A lock can persist for a long period of time: while a page is being scanned, while a disk read or network write takes place, for the duration of a statement, or for the duration of a transaction

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Disk Initialization

Disk initialization is the process of allocating disk space to server. During initialization adaptive server will divide the new allocated disk into allocation units and an entry is made in sysdevices system table.

All the information regarding devices connected to the Server, can be viewed in system table SYSDEVICES.

Device that can be connected to a server was up to 256 till version 12.5, later got unlimited from version 15.

A disk that is allocated to a server cannot be shared with other servers. Any number of databases can use a disk as long as they are in the same server, restricting to a single file system.

Number of devices that can be allocated to the adaptive server depends on the configuration parameter “number of devices”

Disk once initialized to the adaptive server can only be dropped when all the associated databases are dropped

Disk default option for system database has to be turned off.

Syntax Disk init Name = "device_name" , Physname = "physicalname" , [Vdevno = virtual_device_number,] Size = number_of_blocks [, vstart = virtual_address , cntrltype = controller_number] [, contiguous] [, dsync = {true | false}]

ASE 15.0

Disk init name = 'dev2', Physname = '/data/sql_server.dev2',Size = '100M', (vdevno is automatic in 15.0),Directio= trueDefault (dsync = true) - disk writes are guranteed

Note: dsync/directio applied only for File System. Directio is faster than dsync both cannot be used.Maximum devices pre 15.0 256 15.0 onwards 2 million

sp_helpdevice: shows device details sp_dropdevice device_name: drops the device name and will not delete file in file system. Make

sure to drop the database before dropping any device. sp_deviceattr device_name, 'dsync/directio’, {true, false}

Page Header

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GAMNEXTPrevious

AU1 AU2

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New Page Allocation Procedure in ASE

Whenever a user inserts some data it first checks for available pages in the current extent (OAM) and inserts into it. If not found a new extent is allocated for that object in the same allocation unit with the help of the allocation page. This extent is mapped to the OAM of the object. If the extent is not available in the same allocation unit it checks with GAM for a new allocation unit (available extent), allocation page where a new extent can be allocated. After the extent is allocated to the object in a different allocation unit, this extent is mapped with the OAM of the object present in the other allocation unit. If there are no allocation units available for the current requested page in the current GAM, a new GAM is created and later altogether the whole process for new page is processed. If the data exceeds 8GB, new GAM comes into picture. In this way GAM, AU, AP, OAM come into picture when a new request for a page is requested.

Figure 3 Page Allocation Procedure

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Segments

Segment can be describes as the logical name that can be give to a single/fraction/more devices. Two types of segments- System and User System defined- System, Default & Log System- stores all the data related to system tables in that particular database Log- all data modifications in the database are temporarily stored in log Default- stores the data related to user created data objects User defined- A max of 32 segments can be created in a database including the 3 system

segments. SYSSEGMENTS, SYSUSAGES system tables stores detail information regarding the segments, DB

size, etc. The Data and Log segments for a single database should not be placed on a single device in

order to improve the performance and recovery is impossible. Before deleting the segments we should ensure that the objects associated to that segment are

dropped. When we add the additional space to the database system and default segments will

automatically extends on new device where as user created segments has to be manually extended.

There are 3 ways in which we can move tables form one segment to another.o Using bcp- Take a backup of the objects and then copy them back to new segment.o Using clustered index- By re-creating a clustered index for the object on new segment.o Using sp_placeobject – It moves the next upcoming records to the new segment.

Syntax Creates seg_name in the current database and device namesp_addsegment seg_name, db_name, device_name: db_name matches to current database

sp_placeobject segment_name, object_name, db_name: future allocation will be mapped to new segment. Object name can be table name, or index name, ('tab_name.index_name')

sp_helpsegment seg_name: Displays information about all the segments in current database. If specified display information about only one segment which is specified

Sp_dropsegment segment_name, db_name, [device_name]: drops the segment in the current database

Sp_extendsegment, segname, db_name, device_name

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Thresholds

Thresholds monitor the free space in a database and alert the DBA to take appropriate action to prevent the max usage of the database segments coz if neglected the server will hang and is users cannot access.

Thresholds can be defined on data and log segments. Two types of thresholds : System & User

o System level- Last chance Threshold. Usually 18% of log space is reserved for LCT. LCT threshold limit value cannot be modified and is set by the adaptive server automatically. We can only modify the stored procedure Sp_thresholdaction.

o User level- Free chance Threshold. FCT is defined by the user as per the usage of the database and log segment size.

Sp_thresholdaction sends alert if transaction crosses the LCT. A max of 256 thresholds can be created for a Database. All the details regarding the thresholds can be found in SYSTHRESHOLD. FCT’s can be dropped or modified.

Syntax Sp_addthreshold dbname, segname, free_space, proc_name: To add a threshold.Sp_modifythreshold dbname, segname, free_space [, new_proc_name] [, new_free_space] [, new_segname]: To modify a given threshold.

Roles & Groups

Roles provide individual accountability for users performing system administration and security-related tasks. Roles are granted to individual server login accounts, and actions performed by these users can be audited and attributed to them

SYSTEMTABLE: sysroles Groups provide a convenient way to grant and revoke permissions to more than one user in a

single statement. The sp_addgroup system procedure adds a row to Sysusers in the current database. In other

words, each group in a database-as well as each user-has an entry in Sysusers. By default ASE databases has default group as public group. Below are a few descriptions of ROLES-

o System Administrator (sa_role )o System Security Officer (SSO_role)o Operator (oper_role )o Sybase technical support (sybase_ts_role)o Replication (replication_role)o Distributed transaction manager (dtm_tm_role)

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o High availability (ha_role)o Monitor and diagnosis (Mon_role)o Job Scheduler administration (js_admin_role)o Real Time messaging (messaging_role)o Web Services (web_services)o Job scheduler user(js_user_role)

Syntax Create role role_name [with passwd "password"[, {passwd expiration | min passwd length | max failed_logins} option_value] ]: To create a role.Sp_addgroup grpname: To create a group.

Logins & User

SYSLOGIN holds the details which allow people to access the Server level. SYSUSERS holds the details which allow people to access the Databases level. These two above table are related with the column ‘suid’. Syslogins: Suid, dbname, name, password, srvname, procid. Sysusers: Suid, uid, gid, name.

Syntax Sp_addlogin loginame, passwd [, defdb][, deflanguage][, fullname][, passwdexp]: To create a login with a default database.Sp_adduser loginame [, name_in_db [, grpname]]: To create a user for a login for a database.

Interface & Error Log File

An interface file contains network information about all servers on your network, including Adaptive Server, Backup Server, and XP Server, plus any other server applications such as Monitor Server, Replication Server, and any other Open Server applications.

The network information in the file includes the server name, network name or address of the host machine, and the port, object, or socket number (depending on the network protocol) on which the server listens for queries.

Dsedit or Dscp utility are used to create an interface file. Using Dsedit or Dscp is preferred than text editor as it’s easier to use and ensures that the interface file is consistent in format.

Error log is stored externally. All the server level events and severity level >16 will be recorded in the error log.

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We notice error number, severity level >16 and error message in the errorlog. These error messages can be found in the table sysmessages. Severity level less than 17 are not recorded in the error log, as the affect is minimal. Object level

error messages are not included in the error log. We cannot start the ASE without errorlog file.

ASE Memory Usage

Memory is consumed by various configuration parameters, statement cache, procedure cache and data caches.

The total memory allocated during boot-time is the sum of memory required for all the configuration needs of Adaptive Server. The total memory required value can be obtained from the read-only configuration parameter 'total logical memory'.

The configuration parameter 'max memory' must be greater than or equal to 'total logical memory'.

'Max Memory' indicates the amount of memory you will allow for Adaptive Server needs. During boot-time, by default, Adaptive Server allocates memory based on the value of 'total logical memory'. However, if the configuration parameter 'allocate max shared memory' has been set, then the memory allocated will be based on the value of 'max memory'.

Caches in Max Memory / Adaptive Server- o Procedure Cache- Adaptive Server maintains an MRU/LRU (most recently used/least

recently used) chain of stored procedure query plans. As users execute stored procedures, Adaptive Server looks in the procedure cache for a query plan to use. If a query plan is available, it is placed on the MRU end of the chain, and execution begins. If more than one user uses a procedure or trigger simultaneously, there will be multiple copies of it in cache. If the procedure cache is too small, a user trying to execute stored procedures or queries that fire triggers receives an error message and must resubmit the query. Space becomes available when unused plans age out of the cache, the default procedure cache size is 3271 memory pages.

o Statement Cache- The statement cache allows Adaptive Server to store the text of ad hoc SQL statements. Adaptive Server compares a newly received ad hoc SQL statement to cached SQL statements and, if a match is found, uses the plan cached from the initial execution. In this way, Adaptive Server does not have to recompile SQL statements for which it already has a plan. This allows the application to amortize the costs of query compilation across several executions of the same statement. The statement cache memory is taken from the procedure cache memory pool.

o Data Cache- At the point of installation the default data cache is of 2K memory pool. The data cache contains pages from recently accessed objects, typically:

sysobjects, sysindexes, and other system tables for each database Active log pages for each database

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The higher levels and parts of the lower levels of frequently used indexes Recently accessed data pages

The key points for memory configuration are:o The system administrator should determine the size of shared memory available to

Adaptive Server and set 'max memory' to this value.o The configuration parameter 'allocate max shared memory' can be turned on during

boot-time and run-time to allocate all the shared memory up to 'max memory' with the least number of shared memory segments. Large number of shared memory segments has the disadvantage of some performance degradation on certain platforms. Please check your operating system documentation to determine the optimal number of shared memory segments. Note that once a shared memory segment is allocated, it cannot be released until the next server reboot.

o Configure the different configuration parameters, if the defaults are not sufficient.o Now the difference between 'max memory' and 'total logical memory' is additional

memory available for procedure, data caches or for other configuration parameters.o The amount of memory to be allocated by Adaptive Server during boot-time is

determined by either 'total logical memory' or 'max memory'. If this value too high:o Adaptive Server may not start, if the physical resources on your machine does is not

sufficient.o If it does start, the operating system page fault rates may rise significantly and the

operating system may need to re configured to compensate.

Figure 4 How Adaptive Server uses memory

For a good performance, the Hit/Miss ratio should be over 90% and can be found by stored procedure sp_sysmon.

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Db_options To change the default settings for the database we use database options. Sp_dboption- displays or changes database options. List of database options are-

Table 2 System Tables DB Options

SNo. DB OPTION MASTER MODEL TEMPDB SYBSYSTEMPROCS1 abort tran on log full No Yes Yes Yes2 allow nulls by default No Yes Yes Yes3 async log service No No No No4 auto identity No Yes Yes Yes5 dbo use only No Yes Yes Yes6 ddl in tran No Yes Yes Yes7 delayed commit No Yes Yes Yes8 disable alias access No Yes Yes Yes9 identity in nonunique index No Yes Yes Yes10 no chkpt on recovery No Yes Yes Yes11 no free space acctg No Yes Yes Yes12 read only No Yes Yes Yes13 single user No Yes No Yes14 select into/bulkcopy/pllsort No Yes Yes Yes15 trunc log on chkpt No Yes Yes Yes16 unique auto_identity index No Yes Yes Yes

Syntax- sp_dboption [dbname, optname, optvalue [, dockpt]]

Configuration Parameters Config parameter defines the server wide settings and is divided in to static and dynamic. All the static configured parameters values are stored in table sysconfigure. All the dynamic configured parameters values are stored in table syscurconfigure. Config values also stored in the <server name>.cfg file and every time you modify the config

values the current <server name>.cfg file will be saved as <server name>.001 and new config values will be appeared in <server name>.cfg file.

We cannot start the ASE without valid config file. Always have the backup for config file

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Indexes Indexes are created for the faster retrieval of the data. Indexes are preferred when the total

requested records are less than or equal to 5% of total table rows. Whenever a new record is inserted into a table with no index, it stored into the last available

page called hot spot. Table without a clustered index is known a Heap Table. When there is no index on the table the user requested query will perform the table scans

(scanning each page that is allocated to the object). To avoid the table scan we prefer indexes. Indexes can be broadly divided into two types

o Clustered Indexes- There can only one clustered index for a table in binary tree format. The leaf nodes contain the data itself. Data is stored in physical order (asc/desc). Total 3 levels (root, intermediate & data/leaf). Whenever we recreate the clustered index the non-clustered index (if exists) will be automatically recreated and update statistics will run on the object automatically (ASE will run internally).

o Nonclustered Indexes- There can be as many as 249 non clustered indexes for a table. The leaf nodes contain pointers that map to the actual data. This is the reason why it takes more time for nonclustered index data. It is logical. Total 4 levels (root, intermediate. Leaf & data).

All the indexes can be found in table sysindexes for a database. Table is identified by value 0; Clustered index is identified by value 1, where as rest non clustered indexes are identified from 2 to 249.

Diagrams that explain clearly about clustered and non clustered index pages.

Figure 5 Non clustered index

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Figure 6 Clustered Index

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Table 3 Page Split, Overflow Pages, Row Forwarding

Page Split(APL) Overflow Pages Row Forwarding(DOL)If there is not enough room on the data page for the new row, a page split must be performed.

·A new data page is allocated on an extent already in use by the table. If there is no free page available, a new extent is allocated.

·The next and previous page pointers on adjacent pages are changed to incorporate the new page in the page chain. This requires reading those pages into memory and locking them.

·Approximately half of the rows are moved to the new page, with the new row inserted in order.

·The higher levels of the clustered index change to point to the new page.

·If the table also has nonclustered indexes, all pointers to the affected data rows must be changed to point to the new page and row locations.

When you create a clustered index for a table that will grow over time, you may want to use fill factor to leave room on data pages and index pages. This reduces the number of page splits for a time.

Special overflow pages are created for nonunique clustered indexes on all pages-locked tables when a newly inserted row has the same key as the last row on a full data page. A new data page is allocated and linked into the page chain, and the newly inserted row is placed on the new page.

The only rows that will be placed on this overflow page are additional rows with the same key value. In a nonunique clustered index with many duplicate key values, there can be numerous overflow pages for the same value.

The clustered index does not contain pointers directly to overflow pages. Instead, the next page pointers are used to follow the chain of overflow pages until a value is found that does not match the search value.

A data-only-locked table is updated so that it no longer fits on the page, a process called row forwarding performs the following steps:

·The row is inserted onto a different page, and

·A pointer to the row ID on the new page is stored in the original location for the row.

Indexes do not need to be modified when rows are forwarded. All indexes still point to the original row ID.

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Update Stats & Sp_recompile The update statistics helps Optimizer to prepare the best plan for the query based on the

density of the index key value in the sysstatistics table. Execute/schedule update statistics on heavily modified user objects on daily basis. SP_RECOMPILE causes each stored procedure and trigger that uses the named table to be

recompiled the next time it runs.

Syntax update statistics table_name [index_name]. Syntax sp_recompile objname.

Locks & Isolation Level Adaptive Server protects the tables, data pages, or data rows currently used by active

transactions by locking them. Locking is a concurrency control mechanism: it ensures the consistency of data within and across transactions.

Locking affects performance when one process holds locks that prevent another process from accessing needed data. The process that is blocked by the lock sleeps until the lock is released. This is called lock contention.

A deadlock occurs when two user processes each have a lock on a separate page or table and each wants to acquire a lock on the same page or table held by the other process. The transaction with the least accumulated CPU time is killed and all of its work is rolled back.

Adaptive Server supports locking at the table, page, and row level.o Allpages locking, which locks datapages and index pages ,It can acquire just one table-

level lock.o Datapages locking, which locks only the data pages, It can acquire a lock for each page

that contained one of the required rows.o Datarows locking, which locks only the data rows, It can acquire a lock on each row.

Adaptive Server has two levels of locking:o For tables that use allpages locking or datapages locking, either page locks or table locks. o For tables that use datarows locking, either row locks or table locks.

Page and row lockso Shared locks-Adaptive Server applies shared locks for read operations. If a shared lock

has been applied to a data page or data row or to an index page, other transactions can also acquire a shared lock, even when the first transaction is active. However, no transaction can acquire an exclusive lock on the page or row until all shared locks on the page or row are released. This means that many transactions can simultaneously read the page or row, but no transaction can change data on the page or row while a shared lock exists.

o Exclusive locks-Adaptive Server applies an exclusive lock for a data modification operation. When a transaction gets an exclusive lock, other transactions cannot acquire a lock of any kind on the page or row until the exclusive lock is released at the end of its transaction. The other transactions wait or “block” until the exclusive lock is released.

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o Update locks-Adaptive Server applies an update lock during the initial phase of an update, delete, or fetch (for cursors declared for update) operation while the page or row is being read. Update locks help avoid deadlocks and lock contention. If the page or row needs to be changed, the update lock is promoted to an exclusive lock as soon as no other shared locks exist on the page or row.

Table lockso Intent lock-An intent lock indicates that page-level or row-level locks are currently held

on a table. Adaptive Server applies an intent table lock with each shared or exclusive page or row lock, so an intent lock can be either an exclusive lock or a shared lock. Setting an intent lock prevents other transactions from subsequently acquiring conflicting table-level locks on the table that contains that locked page. An intent lock is held as long as page or row locks are in effect for the transaction.

o Shared lock-This lock is similar to a shared page or lock, except that it affects the entire table. A create nonclustered index command also acquires a shared table lock.

o Exclusive lock-This lock is similar to an exclusive page or row lock, except it affects the entire table. For example, Adaptive Server applies an exclusive table lock during create clustered index command. Update and delete statements require exclusive table locks if their search arguments do not reference indexed columns of the object.

Syslocks contains information about active locks, and built dynamically when queried by a user. No updates to Syslocks are allowed.

Deadlock can be tuned with two options – o Deadlock checking period specifies the minimum amount of time (in milliseconds)

before Adaptive Server initiates a deadlock check for a process that is waiting on a lock to be released.

o Deadlock retries specifies the number of times a transaction can attempt to acquire a lock when deadlocking occurs during an index page split or shrink.

Spinlock ratio- A spinlock is a simple locking mechanism that prevents a process from accessing the system resource currently used by another process. All processes trying to access the resource must wait (or “spin”) until the lock is released. If 100 are specified for the spinlock ratio, Adaptive Server allocates one spinlock for each 100 resources. The number of spinlocks allocated by Adaptive Server depends on the total number of resources as well as on the ratio specified. The lower the value specified for the spinlock ratio, the higher the number of spinlocks.

Sp_lock reports information about processes that currently hold locks. Lock promotion can only happen from row to table and page to table level. Config parameters related to locks are :

o Number of lockso Lock schemeo Lock wait periodo Lock spinlock ratioo page lock promotion HWM

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o page lock promotion LWMo page lock promotion PCTo row lock promotion HWMo row lock promotion LWMo row lock promotion PCT

The isolation level controls the degree to which operations and data in one transaction are visible to operations in other, concurrent transactions.

There are four levels of isolation which ASE has, of which level 0 is default. Level 0 –also known as read uncommitted, allows a task to read uncommitted changes to data in

the database. This is also known as a dirty read, since the task can display results that are later rolled back.

Level 1 - also known as read committed, prevents dirty reads. Queries at level 1 can read only committed changes to data. At isolation level 1, if a transaction needs to read a row that has been modified by an incomplete transaction in another session, the transaction waits until the first transaction completes (either commits or rolls back) .

Level 2 – also known as repeatable read. It prevents no repeatable reads. These occur when one transaction reads a row and a second transaction modifies that row. If the second transaction commits its change, subsequent reads by the first transaction yield results that are different from the original read.

Level 3 – also known as serializable reads. It prevents phantoms. These occur when one transaction reads a set of rows that satisfy a search condition, and then a second transaction modifies the data (through an insert, delete, or update statement). If the first transaction repeats the read with the same search conditions.

Phases When Query Is Executed & Process Status When ever a query is executed it is executed in three phases parser, compiler and execute.

Parser checks for the syntactical errors, compiler checks for the query plan in data cache ( if not found gets backs from database), execute checks for the result in the data cache ( if not found gets back from the database).

During the phases of execution, the single process can change to various states depending on the availability of the i/o, query plan, data, etc. Below are mentioned the possible states of a process.

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Table 4 Process Status

Status Condition Effects of kill Command

recv sleep waiting on a network read Immediate

send sleep waiting on a network send Immediate

alarm sleepwaiting on an alarm, such as wait for delay "10:00"

Immediate

lock sleep waiting on a lock acquisition Immediate

Sleeping

Waiting disk I/O, or some other resource. Probably indicates a process that is running, but doing extensive disk I/O

killed when it "wakes up", usually immediate; a few sleeping processes do not wake up, and require a Server reboot to clear

Runnablein the queue of runnable processes

Immediate

Runningactively running on one on the Server engines

Immediate

InfectedServer has detected serious error condition; extremely rare

Kill command not recommended. Server reboot probably required to clear process

Backgrounda process, such as a threshold procedure, run by SQL Server rather than by a user process

Immediate; use kill with extreme care. Recommend a careful check of sysprocesses before killing a background process

log suspendprocesses suspended by reaching the last-chance threshold on the log

killed when it "wakes up": 1) when space is freed in the log by a dump transaction command or 2) when an SA uses the LCT_admin function to wake up "log suspend" processes

If Query Plan found

User

Interface fileASE

ASE E&O

Unused Space

Configuration file

Data Cache

Procedure Cache

Executes Query Parser

Compiler

Execute

Session CreatedUser Log Cache in Shared Memory

Shared Memory

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Hit/Miss Diagram

During the execution of a query, it goes through many phases, which can result as a HIT or a MISS depending on the availability of the data in the cache.

The below diagrams clearly explain the steps involved during HIT or MISS.

Max Memory

Connection Established

Network Handler

Data Fetched back to USER

Send Sleep HIT

Receive Sleep

Running

1. Connection is established between user and the ASE.2. A new session is created for the user.3. When a query is fired, it is passed to parser, next to complier and then executed till the result is

fetched back to the user.4. Parser checks for syntactical errors, compiler checks for existing query plan in procedure cache,

execute checks for the corresponding data in the data cache. 5. If everything is found where expected, it’s called a HIT.

Figure 7 Steps when a Query is executed by a USER --- HIT

SYSSTATISTICS

UPDATE STATS

SYSQUERYPLANSTABLE

DISK

Optimizer prepares Query Plan

User

Interface fileASE

ASE E&O

Unused Space

Configuration file

Data Cache

Procedure Cache

Executes Query

Parser

Compiler

Execute

Session CreatedUser Log Cache in Shared Memory

Shared Memory

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Max Memory

Connection Established

Network Handler

Data Fetched back to USER

Send Sleep MISS

Receive Sleep Sleeping

If query plan not found

Running

1. Connection is established between user and the ASE, 2. A new session is created for the user.3. When a query is fired, it is passed to parser, next to complier and then executed till the result is

fetched to the user.4. Parser checks for syntactical errors, compiler checks for query plan in the procedure cache, if

not found it gets prepared by the optimizer, execute checks for data in data cache and if not found gets from the disk and sent back to user.

5. If any one of them (data or query plan) is not found where expected, it’s called a MISS.

Figure 8 Steps when a Query is executed by a USER --- MISS

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Start and Shut Down Of Server To start the ASE execute startserver –f RUN_<server name>. Use – m to start the server in single

user mode. The following examples show the RUN_servername file edited to start an Adaptive Server

named TEST in single-user mode On UNIX-o #!/bin/sho #o # Adaptive Server Information:o # name: TESTo # master device: /work/master.dato # master device size: 10752o # errorlog: /usr/u/sybase/install/errorlogo # interfaces: /usr/u/sybase/interfaceso #o /usr/u/sybase/bin/dataserver -d/work/master.dat o -sTEST -e/usr/u/sybase/install/errorlog o -i/usr/u/sybase/interfaceso -c/usr/u/sybase/TEST.cfg –m

Use –P option in run server file to generate the password for the SA which prints the new SA password in the errorlog, for this we need to reboot the ASE server.

Once the configuration file is loaded, it creates memory in the shared memory and creates the file <server name>.krg. Solaris\Unix or any environment, allocates shared memory for the ASE server. In version 12.5.3 a max of 3.7 GB can be allocated to the ASE server.

IPC does the job of controlling and monitoring the shared segments of shared memory. Shut down of a server can be in two modes. <Server name>.krg file will be automatically deleted

when ASE server goes offline.o Wait- it’s a clean shut down which checks and ensures that all transactions are closed. o Nowait- It’s a don’t care shut down, which kill all the transactions forcefully.

Backup/Recovery/Refresh/Restore Recovery- Getting the database to the current state of data from a previously maintained

backup. Refresh- Loading data from one database to another irrespective of sever. Restore- Taking the database to a previous state. Backup- Taking an extra copy of the existing data.

Steps to be followed for test refresh. Take backup for Prod and Test DB, and also db_options for the test should be saved before the

refresh operation. BCP out the tables SYSUSERS, SYSPROTECTS and SYSALIASES from Test DB. Bcp test.dbo.sysusers out <file name> -Ulogin –Sserver –Ddatabase.

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Bcp test.dbo.sysprotects out <file name> -Ulogin –Sserver –Ddatabase. Bcp test.dbo.sysaliases out <file name> -Ulogin –Sserver –Ddatabase. For copying the ddl of a table the command use ddlgen –Ulogin –Ppassword -S[server] –

T[object_type] (if user requested to take the backup for specific tables). Load the Test DB with Prod DB backup. To modify the system table configure the parameters- sp_configure “allow updates on system

tables”, 1. Delete the rows from sysusers excluding dbo user-Delete from sysusers where name not in

(‘dbo’). For copying back the data to sysusers, sysprotects table we need to execute- Bcp test.dbo.sysusers in<path> -Ulogin –Sserver –Ddatabase. Bcp test.dbo.sysprotects in<path> -Ulogin –Sserver –Ddatabase. To reconfigure the access parameters to system tables - sp_configure “allow updates on system

tables”, 0. Online database database name. Set the db_options for the database. Remap the users after load/refresh

Run dbcc and update stats on need basis.

Dbcc Database consistency checker (dbcc) checks the logical and physical consistency of a database

and provides statistics, planning, and repair functionality. dbcc Tablealloc checks the specified user table to ensure that-

o All pages are correctly allocated.o Partition statistics on the allocation pages are correct.o No page is allocated that is not used.o All pages are correctly allocated to the partitions in the specified table and no page is

used until allocated.o No page is used that is not allocated.

dbcc Checkalloc ensures that-o All pages are correctly allocatedo Partition statistics on the allocation pages are correcto No page is allocated that is not usedo All pages are correctly allocated to individual partitions and no page used until

allocated.o No page is used that is not allocatedo dbcc Checkalloc [(database_name [, fix | nofix] )]

dbcc Tablealloc checks the specified user table to ensure that-

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o All pages are correctly allocated.o Partition statistics on the allocation pages are correct.o No page is allocated that is not used.o All pages are correctly allocated to the partitions in the specified table and no page is

used until allocated.o No page is used that is not allocated.

dbcc indexalloc checks the specified index to see that-o All pages are correctly allocated.o No page is allocated that is not used.o No page is used that is not allocated.

dbcc CheckTable checks the specified table to see that-o Index and data pages are linked correctly.o Indexes are sorted properly.o Pointers are consistent.o All indexes and data partitions are correctly linked.o Data rows on each page have entries in the row-offset table; these entries match the

locations for the data rows on the page.o Partition statistics for partitioned tables are correct.

Dbcc checkdb runs the same checks as dbcc CheckTable on each table in the specified database. If you do not give a database name, dbcc checkdb checks the current database. dbcc checkdb gives similar messages to those returned by dbcc CheckTable and makes the same types of corrections.

DBCCDB database setupo Determine Size – sp_plan_dbccdb.o Initialize Disk Devices- Based on size create data and log devices.o Create dbccdb Database- Create dbccdb on the above created devices.o Install Stored Procedures- isql -Usa -P -SASESERVER –iinstalldbccdb -odbccdb_error.out.o Configure Adaptive Server- sp_configure "number of worker processes", 2.o Create Workspaces.o Set dbccdb Configuration Parameters.o Run dbcc checkstorage.o Evaluate Configurations.

PROXY TABLES Sp_addserver PROX_<server name>,NULL,<server name that u mention in interface file> Sp_addexternlogin PROX_<server name>, <login name in source server>, <user at remote

server>, <password at remote server> Sp_addobjectdef proxy_<table name>, “PROX_<server name>,<remote database

name>,<remote object owner>,<object name>”,”table”

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Create proxy_table , proxy_<table name> at “PROX_<server name>,<remote database name>,<remote object owner>,<object name>”

MDA Tables MDA tables provides detailed information about server status, the activity of each process in the

server, the utilization of resources such as data caches, locks and the procedure cache, and the resource impact of each query that’s run on the server.

Steps that need to be followed during installing MDA tables-o Check for sp_configure ‘enable cis’ and set to 1.o Add ’loopback’ server name alias in master - sp_addserver loopback, null,

@@servernameo Install MDA tables - isql -U sa -P <password> -S<Server Name> –i

~/scripts/installmontableso Assign 'Mon_role' to logins allowed MDA access- grant role Mon_role to sao To test for basic configuration – select * from master..monstateo Assign several configuration parameters like enable monitoring to 1, sql text pipe active

to 1, sql text pipe max messages to 100, plan text pipe active to 1, plan text pipe max messages to 100, statement pipe active to 1, statement pipe max messages to 100, errorlog pipe active to 1, errorlog pipe max messages to 100, deadlock pipe active to 1, deadlock pipe max messages to 100, wait event timing to 1, process wait events to 1, object lockwait timing to 1, sql batch capture to 1, statement statistics active to 1, per object statistics active to 1, max sql text monitored to 2048

Multiple Temp Databases Multiple tempdb is useful when a user or an application needs specified tempdb, for its

operations. If in any case if the rest tempdb are full, the default tempdb would be helpful in getting back the rest to normal operations. The default tempdb is usually assigned to the SA, to avoid server tempdb full. The number of user created tempdb can be configured according to the available hard ware resources and the user application.

Steps to be followed during creation of tempdb-o Creating devices for tempdb - Create temporary database <temp db name> on <device

name>=<size on device>Log on <log device name>=<size on device>.o To add the database as a tempdb- Sp_tempdb add, <tempdb name>, ‘default’.o To bind the tempdb - sp_tempdb ‘bind’, ‘lg’, ’<login name>’, ’db’. ‘<Tempdb name>.o To unbind the tempdb - sp_tempdb ‘unbind’, ‘lg’, ’<login name>’, ’db’. ‘<Tempdb

name>.

Utilities Optdiag -Displays optimizer statistics or loads updated statistics into system tables.

The advantages of Optdiag are-o Optdiag can display statistics for all tables in a database, or for a single table.

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o Optdiag output contains addition information useful for understanding query costs, such as index height and the average row length.

o Optdiag is frequently used for other tuning tasks, so you should have these reports on hand.

Isql - Interactive SQL parser to Adaptive Server.Syntax –isql –Uuser –Sserver –Ddatabase.When connecting to the server with isql, it goes to the file (sql.ini for Windows/interface.ini for Solaris), and finds the path for the server.

ddlgen- This is used to take a back up of a table structure Defncopy- This is used to take a backup of defaults, views, rules stored procedures and triggers. Bcp – two options in and out. Out is to extract the data from the e object to flat file and In is vice

versa. Again In have two options, fast bcp (non-logged) and slow bcp (logged). For copying back the data the option must be set to true- sp_dboption “select into /pllsort”, true.

Troubleshooting If server config value has reached the max threshold limit for ‘number of open databases’,

‘number of open objects’, ‘number of open indexes’, ‘number of user connections’ & ‘number of locks’. Please follow the steps below.

Sp_countmetadata- Gives information about the total number of objects like tables, sp’s, views, triggers, etc. sp_countmetadata "configname" [, dbname].

Sp_monitorconfig- Gives information about max usage/current max value of the above mentioned config parameters.

Sp_configure- To reconfigure the parameters with new value. To check if the port is opened

Telnet <IP ADDRESS> <Port Number>if the port is opened you will see a blank screen in command prompt....

To abort all the open transactions when log is full- Select LCT_admin(abort, pid, dbid).

Process to kill the open transactions

a. The PID for the current running transaction can be identified from table SYSLOGSHOLD.b. Once the PID is identified, the user details can be found from the table SYSPROCESSES.c. Execute dbcc TRACEON (3604): Turning on the trace flag will display the trace output on

console rather than the error log. d. Execute dbcc SQL TEXT (spid) : to view the details of the transactione. Execute dbcc TRACEOFF (3604)f. To Kill Process- kill PID.

To view server status in Unix- showserver, & ps-esf |grep Sybase. To know server version details- select @@version OR records in error log OR dataserver –v. To know the current isolation level used by the server- select @@isolation. For manually clearing shared segments- ipcrm –s/m<pid> and verify the values with <server

name>.krg file and once you clear the memory then delete the <server name>.krg file.

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Also check for any active Sybase process ps –eaf |grep Sybase. Kill the active Sybase process related to the particular server.

Memory Jam- It occurs due to the non de-allocation of the shared segments in the shared memory.

To recover this we have to check out the number of servers running. Later we have to match the <servername>.krg file with the details available on the shared segment allocated to the server.

Delete the identified segment by using- ipcrm –s<PID>. It’s always a better practice to hold a backup of the <servername>.krg file, as it is deleted once

the server gets shut down.

Checking the server blocking process

a. When a process A is blocked by another process B, and B blocked by C, and continued in similar fashion till N number of processes, these all are blocked by the nth process. To unblock process A, all the sub processes till Nth process should be killed or terminated.

b. To retrieve the blocked and corresponding blocking process id’s, a correlated query on sysprocess table, has to be executed.

c. Check the final process id dbcc dbcc traceon(3604)godbcc (sqltext <pid>)dbcc dbcc traceoff(3604)go Or dbcc set tracefile “<file-path>” for spidgoset show_sqltext onset showplan ongosp_helpapptracego dbcc set tracefile off for spid go

d. If it’s a select operation, kill the process. Or else wait till the operation is completed.

Recovering Master Database

a. Recovering master Database can be done only if a valid dump of Master database exists.b. To build it again, steps followed are

i. Dataserver –d<device name> -z<page size> -b<size>.ii. User should log into the server, in single user mode.

iii. Load the Master DB from previous backup.iv. Restart the server.

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c. Backups of Necessary tables like syslogins, sysusages, sysdevices, sysdatabases, and sysalternatives should always be maintained.

Point-In-Time Recovery

a. PITR can be done only if a valid full dump of database, transaction log dumps and the dump of current transaction log (dump tran <db name> to ‘<file name>’ with no_truncate, this option will allow to perform the backup if database device fails.).

b. To do PITR, steps followed arei. Restore the full backup

ii. Restore all the transaction logs in the sequenceiii. Restore the most recent transaction log which was dumped with no_truncate

optioniv. Bring the database online.

Extending Temp Database to separate data and log segments

a. Initialize data and log devices separatelyb. Extend Temp database to these devicesc. Sp_configure ‘allow updates’, 1 – Allows updating the sysusages table.d. Delete from sysusages where dbid=2 and segmap=<the segment id for master device>e. Sp_configure ‘allow updates’, 0f. Sp_helpdb tempdb- Shows the details for the Temp database.

Log free space issue (showing minus value in log segment usage)

log on to Sybase server

Use masterGoSp_stop_rep_agent <database name >go

Logon to replication server

admin healthgosuspend connection to goadmin whogoadmin healthgoadmin disk_spacego


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use mastergosp_dboption <database name >, ‘dbo use’,truegosp_dboption <database name >, ‘single user’,truegoselect spid from sysprocesses where dbid=db_id(‘<database name >’)go(if find any active process kill them)use <database name >gocheckpointgodbcc traceon(3604)godbcc dbrepair(<database name >,’fixlogfreespace’)godbcc traceon(3604)gouse mastergosp_dboption <database name >, ‘dbo use’,falsegosp_dboption <database name >, ‘single user’,falsego

Logon to replication server

admin healthgoresume connection to goadmin whogoadmin healthgoadmin disk_spacego


use mastergosp_start_rep_agent <database name >go

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TIPS To find the ROWID

select rownum = identity(10) , <column name> into #<temp table name> from <table name>select * from #<temp table name>drop #<temp table name>go

How to Apply EBF Sybase releases a bulletin and lists the details of the updates and bug fixes (EBF details) for each

version of Sybase server. All of these patches / hot fixes are bundled in a package and released with the list of bugs fixed or enhancements of the product

Process for Patch Deployment:a. Download the patches from the Sybase Site. b. Create a temporary directory, and unzip the patch file into this directory. For DOS

installations set the temporary directory as your current directory and run setup.exe in that directory. For Windows installations, double click on setup.exe from the explorer in the temporary directory.

c. The patch ZIP file contains a file called README.TXT. This is a text file documenting bug fixes and changes that were made to this release of the software.

d. Evaluate the Patches and verify is the patch is suitable for your current version.e. Classify them into required and not required. Any patch that is presumed not to be

necessary for deployment now can be ignored as the final version of this hot fix will be rolled out in the next service pack of the product.

f. Run basic DBCC checks to make sure the all the databases are in good condition. If you find any error in DBCC output fix the issue before rolling out the new patch.

g. Take a backup of all the system, user databases and BCP out of specific system tables. h. Lock all the users on the data server as we need to perform some post install steps i. Bounce the Serverj. Deploy the required patches in the test environment.k. Run standard upgrade scripts like installmaster, installmsgs, installmontables from

$SYBASE/ASE_125/scriptsl. Verify the output for any issues.m. Change the $SYBASE variable in .profile to point to new EBF directory and source itn. Copy the run server file into the new location ( if required since most of the clients keep

the run server file in $SYBASE/ASE/install )o. Bring up the Server.p. Verify the errorlog for any issues.q. Validate the errorlog and fix the issues with applications.r. unlock all the users and handover the server to apps team

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s. If any of the hot fix is causing undesired results do not deploy the fix until further testing.

t. Once the test environment looks stable with the new patch deployments and all issues seen during the deployment are resolved the same can be moved to production.

u. Document all the steps, observations and workarounds that have been carried out during the testing phase.

v. Prepare a Checklist.w. Plan for roll out into production.

Query and Server Performance Tuning Below are some tools for Query Tuning

a. Show Plan- tells you the final decisions that the optimizer makes about your queries.b. Set Show Plan – to turn the show plan off or onc. Set Statistics I/O – displays the number of logical and physical reads and writes required

for each table in a query. If resource limits are enabled, it also displays the total actual I/O cost.

d. Dbcc trace on (3604, 302) - makes you understand why and how the optimizer makes choices. It can help you debug queries and decide whether to use certain options, like specifying an index or a join order for a particular query.

e. Dbcc trace on (3604, 310) - gives per table I/O estimates.f. Dbcc trace on (3604, 317) - gives report about all the plans.g. Set no exec on- prepares the query plan with out executing the query.

Below are some points to be taken care for better performancea. Data and Log of tempdb should be placed on different devices.b. Data and log of user databases should also be placed on different devices.c. Data cache should be configured such that hit/miss ratio should be greater than 90.d. Statistics must be updated periodically, and also exec sp_recompile.e. Run update index statisticsf. All Nonclustered Indexes should be placed on a separate segment.g. All lookup tables should be placed on a separate segment.h. Indexes should be proper. Reorg/Recreate if necessary.i. Run reorg forward_row/reorg rebuild (select “reorg rebuild” +name+char(10)+”go”

from sysobjects where type=’U’ and lockscheme(name) not it (‘allpages’)

Sp_monitor - Displays statistics about Adaptive Server. Adaptive Server keeps track of how much work it has done in a series of global variables. Sp_monitor displays the current values of these global variables and how much they have changed since the last time the procedure executed.

Sp_sysmon - Displays performance information, displays information about Adaptive Server performance. It sets internal counters to 0, and then waits for the specified interval while

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activity on the server causes the counters to be incremented. When the interval ends, sp_sysmon prints information from the values in the counters.

If you face the performance issues.Check the physical_io in sysprocesses table and trace the spid detailsDbcc traceon(3604)Dbcc sqltext(spid)Sp_whoSp_lockSp_object_stats “00:10:00”Sp_monitorconfig “all”

Calculations To find vdev number- Select max (low/16777218) from Master..sysdevices. Procedure cache size= (max number of concurrent users)*(4+size of largest plan)*1.25. Minimum procedure cache size needed=(number of main procedures)*(Average plan size). To get a rough estimate of the size of a single stored procedure, view, or trigger, use:

select(count(*) / 8) +1 from sysprocedures where id = object_id("procedure_name"). number of worker processes = [max parallel degree] X [the number of concurrent connections

wanting to run queries in parallel] X [1.5]. Size of the tempdb = 20% of sum up of all the user databases. Size of Log disk= 10 % of the data disk of the particular device. Size of DBCC database- can be found out from sp_plan_dbccdb. Stored procedure to get the segment usage report

SQL to calculate database usageselect "Database," = convert(char(20),db_name(dbid))+',',"Data Size," = str(sum(size * abs(sign(segmap - 4))) / 512.0, 7, 2)+',',"Data Used," = str(sum((size - curunreservedpgs(dbid, lstart, unreservedpgs)) * abs(sign(segmap - 4))) / 512.0, 7, 2)+',',"Data Free," = str(100.0 * sum((curunreservedpgs(dbid, lstart,unreservedpgs)) * abs(sign(segmap - 4))) / sum(size * abs(sign(segmap- 4))), 3) + "%"+',',"Log Size," = str(sum(size * (1 - abs(sign(segmap - 4)))) / 512.0, 7, 2)+',',"Log Used," = str(sum((size - curunreservedpgs(dbid, lstart, unreservedpgs))* (1 - abs(sign(segmap - 4)))) / 512.0, 7, 2)+',',"Log Free" = str(100.0 * sum((curunreservedpgs(dbid, lstart,unreservedpgs))* (1 - abs(sign(segmap - 4)))) / sum(size * (1 - abs(sign(segmap - 4)))), 3) + "%"from master..sysusages

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where segmap < 5group by db_name(dbid)

SQL to find the database and the related devicesselect dbid, size,name, phyname "physical device"from sysusages, sysdevices where name = 'xxx' and vstart between low and high compute sum(size)go

SQL to find the max CPU utilizedSelect spid,suser_name(suid),hostname,program_name,physical_io,memusage,ipaddr from sysprocesses order by physical_iogoSelect name,accdate,totcpu,totio from syslogins order by totcpugo

Entry in interface file - master tli tcp /dev/tcp \x0002 0401 81 96 c451.

This can be interpreted as- X0002 no user interpretation (header info?) 0401 port number (1025 decimal) 81 first part of IP address (129 decimal) 96 second part of IP address (150 decimal) c4 third part of IP address (196 decimal) 51 fourth part of IP address (81 decimal)

Sybase Diagram

Replication Overview and Architecture Diagram Sybase Replication Agent is the Sybase solution for replicating table data changing operations

and stored procedure invocations against a primary database. Sybase Replication Agent extends the capabilities of Replication Server by allowing non-Sybase

(heterogeneous) database servers to act as primary data servers in a replication system based on Sybase replication technology.

Rep Server is configured by using command rs_init. Primary Dataserver - It is the source of data where client applications enter/delete and modify

data. This need not be ASE; it can be Microsoft SQL Server, Oracle, DB2, and Informix. Replication Agent/Log Transfer Manager- Log Transfer Manager (LTM) is a separate

program/process which reads transaction log from the source server and transfers them to the replication server for further processing. With ASE 11.5, this has become part of ASE and is now

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called the Replication Agent. However, you still need to use an LTM for non-ASE sources. When replication is active, one connection per each replicated database in the source dataserver (sp_who).

Replication Server (s) - The replication server is an Open Server/Open Client application. The server part receives transactions being sent by either the source ASE or the source LTM. The client part sends these transactions to the target server which could be another replication server or the final dataserver.

Replicate (target) Dataserver – It is the server in which the final replication server (in the queue) will repeat the transaction done on the primary. One connection for each target database, in the target dataserver when the replication server is actively transferring data (when idle, the replication server disconnects or fades out in replication terminology).

Stable Queue- after Replication Server is installed; a disk partition is set up used by Replication Server to establish stable queues. During replication operations, Replication Server temporarily stores updates in these queues. There are three different types of stable queues, each of which stores different type of data.

o Inbound Queue- holds messages only from a Replication Agent. If the database you add contains primary data, or if request stored procedures are to be executed in the database for asynchronous delivery, Replication Server creates an inbound queue and prepares to accept messages from a Replication Agent for the database.

o Outbound Queue- holds messages for a replicate database or a replicate Replication Server. There is one outbound queue for each of these destinations:

For each replicate database managed by a Replication Server, there is a Data Server Interface (DSI) outbound queue.

For every Replication Server to which a Replication Server has a route, there is a Replication Server Interface (RSI) outbound queue.

o Subscription Materialization Queue- holds messages related to newly created or dropped subscriptions. This queue stores a valid transactional “snapshot” from the primary database during subscription materialization or from a replicate database during dematerialization.

Stable Queue Manager manages all these operations related to Stable Device. Data Server Interface- It connects RDS and Rep Server. It reads data from Outbound Queue and

replicates to RDS according to the subscriptions. Distributor- It takes care of sending committed transaction from inbound queue to outbound

queue with the help of Stable Queue Transaction (SQT) Reader. Any exceptions encountered during the process are recorded into rs_exception.

o Whenever two servers required to be connected over WAN, they both have to be set into a single domain.

o If Rep Servers are more than 10, Rep monitoring service (RMS) is required to manage all of them. Otherwise they are managed by Replication Manager.

o There can be multiple rep definitions for a single table.o Multiple servers can be connected in two ways- Hierarchal and Star.

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o The time to reach from PDS to RS is known as latency.

LOG TRANSFER LANGUAGE

REPLICATION SERVER

REP AGENT LOG

DATA SERVER INTERFACE

STABLE DEVICE

Stable QueueManaged by Stable Queue Manager

Subscriptions

AM

NAM

NM

BM

REPLICATE DATA SERVERPRIMARY DATA SERVER

Rep Definition

Transaction log

Secondary Transaction Point found in rs_loacter

Committed Transactions

DISTRIBUTORStable Q

ueue Transaction ReaderINBOUND QUEUE OUTBOUND QUEUE

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Figure 9 Replication Architecture

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Sybase License DefinitionLicense Definitions

Crontab Job scheduling at UNIX level is done in crontab. All the DBA jobs are scheduled to run

automatically in crontab. Each user on UNIX level has own crontab and one should have the privilege to add/modify the crontab.

Syntax- crontab [ -e [opens the crontab editor] | -l [lists all the crontab entries] | -r [removes the crontab file].

Always have the backup for crontab.

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sybase dba user guide for beginners

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