The Sybase IQ server does not wait for additional space on an out-of-dbspace condition, but instead rolls back either the entire transaction or rolls back to a savepoint. If there is not enough temporary or main dbspace available for a buffer or dbspace allocation request, then the statement making the request rolls back.
At this point, the DBA can add more space to a dbspace using the ALTER DBSPACE or the ALTER FILE command. (You may choose to add files instead of dbspaces. A single dbspace can have multiple dbfiles.)
WARNING! If Sybase IQ holds certain system locks or is performing a checkpoint when you run out of disk space, you may not be able to add disk space. For this reason, recognizing when you are low on disk space and adding a new dbspace before you run out of space are important.
For examples of using event handlers to monitor disk space usage, see the section “Monitoring disk space usage”.
Check recent messages in the Sybase IQ message log (dbname.iqmsg). If you see an “out of space” message, you must add another dbspace. The message in the Sybase IQ message file indicates which dbspace has run out of space. If the problem occurs while you are inserting data, you probably need more room in the IQ main store. If the problem occurs during queries with large sort-merge joins, you probably need more room in the IQ temporary store.
Check the Sybase IQ message log for the following messages:
If a buffer or dbspace allocation request fails because there is no space in the dbspace, the following error message is logged in the dbname.iqmsg message file:
You have run out of space in %2 DBSpace. %1
[EMSG_OUT_OF_DBSPACE: SQL Code -1009170L, SQL State QSB66, Sybase Error Code 20223]
where %2 is the name of the dbspace.
This error messages replaces the error message You
have run out of { IQ STORE | IQ
TEMPORARY STORE } dbspace in database <dbname>.
In another session, please issue a CREATE DBSPACE ... { IQ
STORE | IQ TEMPORARY STORE } command
and add a dbspace of at least nn MB.
If the entire transaction is rolled back on an out-of-dbspace condition, the following error message is reported:
%1 -- Transaction rolled back"
[IQ_TRANSACTION_ROLLBACK: SQL Code -1285L, SQL State 40W09, Sybase Error Code 2973]
where %1 is the error that caused the transaction to roll back, when encountered by the server during a critical operation.
If a buffer allocation request finds a dirty buffer, but the buffer manager cannot flush the buffer due to an out-of-space condition, the following error message is returned and the current statement rolls back:
%2: All buffer cache pages are in use, ask your DBA to increase the size of the buffer cache. %1
[EMSG_BUFMAN_ALLSLOTSLOCKED: SQL Code -1009031L, SQL State QSA31, Sybase Error Code 20052]
where %2 is the particular buffer cache throwing the exception.
Try to connect to the database from a new connection. If this works, you know that the database server is running, even though the query is waiting. Run sp_iqstatus to get more information.
If you cannot connect to the database, check if Sybase IQ is in an unusable state by monitoring the CPU usage for that processor. If the CPU usage does not change over a small time interval, then Sybase IQ is probably not operational. If the CPU usage does change, Sybase IQ is operational.
Check the sp_iqstatus output for the following two lines:
Main IQ Blocks Used:,10188 of 12288, 82%, Max Block#: 134840
Temporary IQ Blocks Used:,163 of 6144, 2%, Max Block#: 97
If the percentage of blocks used is in the nineties, you need to add more disk space with the CREATE DBSPACE command. In this example, 82% of the Main IQ Blocks and 2% of the Temporary IQ Blocks are used, so more space will soon be needed in the IQ main store.
If out-of-space conditions occur or sp_iqstatus shows a high percentage of main blocks in use on a multiplex server, run sp_iqversionuse to find out which versions are being used and the amount of space that can be recovered by releasing versions. For details, see “sp_iqversionuse procedure” in Chapter 7, “System Procedures,” Reference: Building Blocks, Tables, and Procedures.
Start in forced recovery mode and add space as soon as possible. You must add a dbspace before any new checkpoints can succeed. See “Starting servers in forced recovery mode”. For multiplex servers, see Using Sybase IQ Multiplex.
If Sybase IQ has already run out of space when a checkpoint is requested, the checkpoint command fails with the error:
You have run out of space during the CHECKPOINT operation.
[EMSG_IQSTORE_OUTOFSPACE_CHECKPOINT:'QSB33', 1009133].
You must add a dbspace before any new checkpoints can succeed.
If you run out of space during an operation and are unable to add space because you cannot connect to the server, you must:
Shut down the database server using any of these methods:
On any platform, run dbstop.
On Windows, click the correct server icon on the Windows task bar to display the Sybase IQ window, and then click the Shutdown button.
On UNIX, run stop_iq or
type q in the window where
the server was started.
If the server does not shut down, see “Server fails to shut down” below.
Restart the engine with the start_iq command.
Connect to the database.
Use the CREATE DBSPACE command to add space.
Rerun the operation that originally failed due to insufficient space.
Growth of catalog files is normal and varies depending on application and catalog content. The size of the .db file does not affect performance, and free pages within the .db file are reused as necessary. To minimize catalog file growth:
Avoid using IN SYSTEM on CREATE TABLE statements.
Issue COMMIT statements after running system stored procedures.
Issue COMMIT statements after long-running transactions
If the catalog store cannot extend one of its files (.tmp, .db, or .iqmsg), Sybase IQ returns
the error A dbspace has reached its maximum
file size. To prevent this problem:
Monitor space usage periodically.
Verify that there are no operating system file size limits (such as Sun Solaris ulimit) where the .tmp, .db, or .iqmsg files are located. The .db and .tmp files are typically in the main Sybase IQ database directory. The .tmp file is located under $IQTMP15/<servername>/tmp, or if $IQTMP15 is not set, under /tmp/.SQLAnywhere/<servername>/tmp.
If the temporary dbspace runs out of space and you accidentally omit the TEMPORARY keyword in the CREATE DBSPACE command, you cannot create a temporary dbspace. Instead, add the file in the existing temporary dbspace as IQ_SYSTEM_TEMP.
Sybase IQ provides control over fragmentation by taking advantage of even the smallest unused spaces. However, fragmentation can still occur. If your database runs out of space, even though Mem Usage listed by sp_iqstatus or the .iqmsg file shows Main IQ Blocks Used is less than 100%, it usually indicates that your database is fragmented,
Note that when a connection is out of space, freeing space by dropping tables or indexes in another connection is not possible, because the out of space transaction will see those objects in its snapshot version.
Recognizing when the server is low on disk space and adding a new dbspace before the server runs out of space is important. See the section “Monitoring disk space usage” for examples of using event handlers to monitor disk space usage and to notify you when available space is low.
Sybase IQ automatically reserves the minimum of 200MB and 50 percent of the size of the last dbspace.
To ensure that you have enough room to add new dbspaces if you run out of space in the future, set the database options MAIN_RESERVED_DBSPACE_MB and TEMP_RESERVED_DBSPACE_MB. Set these options large enough to handle running out of space during a COMMIT or CHECKPOINT. See Chapter 2, “Database Options,” in Reference: Statements and Options for details.
