Add the ability to specify in the isc_dsql_fetch (or in another API) how many
records need to be prefetched from the server
---------------------------------------------------------------------------------------------------------------------------
Key: CORE-6013
URL: http://tracker.firebirdsql.org/browse/CORE-6013
Project: Firebird Core
Issue Type: Improvement
Components: API / Client Library
Affects Versions: 4.0 Beta 1
Reporter: Rashid Abzalov
Add the ability to specify in the isc_dsql_fetch (or in another API) how many
records need to be prefetched from the server.
This feature will allow to avoid the fragmentation of the on the network, as
well as to avoid multiple context switching during server calls to fetch next
several records.
As a result, this leads to an increase of the client application performance
and a reduction multiple but small calls to the server — the select will be
processed in large parts, and there will be no need to return to it many times.
I know that in the current implementation, Firebird independently returns as
many records as fit in the packet of server exchange protocol.
But:
- in some cases it may be necessary to more finely manage the number of
returned records (based on the specifics of the application)
- this does not solve the problem of network fragmentation
- this makes it impossible for the server to process the request in bulk,
rather than returning to it many times
- this does not solve the problem of permanent round-trip to the server to
retrieve next records. Instead of one request and one big answer (let it be
fragmented in parts, but sent at one time)
A similar feature is available in Oracle and Postgres.
Oracle documentation -
https://docs.oracle.com/cd/B28359_01/appdev.111/b28395/oci04sql.htm#i429698
(see OCI_ATTR_PREFETCH_ROWS)
Postgres documentation - https://www.postgresql.org/docs/9.6/sql-fetch.html
(see FORWARD count)
Oracle has 2 options:
1) use of OCI_ATTR_PREFETCH_ROWS - the requested number of records is cached
in the client library internal buffer (oci.dll).
Then, on the next OCIStmtFetch calls, the records are taken from the
internal buffer, and not requested from the server until the buffer is empty.
2) the ability to get an array of records immediately to the client's
application buffer (not the client library internal buffer).
Postgres has only 1 option:
1) obtaining an array of records from the server to the client library
internal buffer.
Then, the user application can access the row values of the records by
index.
If necessary, the application can request the next portion of the array of
records that will overwrite the current contents of the buffer.
--
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators:
http://tracker.firebirdsql.org/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira
Firebird-Devel mailing list, web interface at
https://lists.sourceforge.net/lists/listinfo/firebird-devel
