Horton

Re: PATCH: logical_work_mem and logical streaming of large in-progress transactions

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Erik Rijkers <er@xs4all.nl>, Kuntal Ghosh <kuntalghosh.2007@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Michael Paquier <michael@paquier.xyz>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2020-06-17T10:26:01Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Tighten the concurrent abort check during decoding.

  2. Improve hash_create()'s API for some added robustness.

  3. Use HASH_BLOBS for xidhash.

  4. Fix initialization of RelationSyncEntry for streaming transactions.

  5. Remove unused function declaration in logicalproto.h.

  6. Add additional tests to test streaming of in-progress transactions.

  7. Fix inline marking introduced in commit 464824323e.

  8. Add support for streaming to built-in logical replication.

  9. Fix the SharedFileSetUnregister API.

  10. Fix comment in procarray.c

  11. Suppress compiler warning in non-cassert builds.

  12. Extend the BufFile interface.

  13. Mark a few logical decoding related variables with PGDLLIMPORT.

  14. Implement streaming mode in ReorderBuffer.

  15. Extend the logical decoding output plugin API with stream methods.

  16. WAL Log invalidations at command end with wal_level=logical.

  17. Immediately WAL-log subtransaction and top-level XID association.

  18. Allow logical replication to transfer data in binary format.

  19. Only superuser can set sslcert/sslkey in postgres_fdw user mappings

  20. Track statistics for spilling of changes from ReorderBuffer.

  21. Add logical_decoding_work_mem to limit ReorderBuffer memory usage.

  22. logical decoding: process ASSIGNMENT during snapshot build

  23. Emit invalidations to standby for transactions without xid.

On Tue, Jun 16, 2020 at 2:36 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Mon, Jun 15, 2020 at 6:29 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > I have few more comments on the patch
> > 0013-Change-buffile-interface-required-for-streaming-.patch:
> >
>
> Review comments on 0014-Worker-tempfile-use-the-shared-buffile-infrastru:
>

changes_filename(char *path, Oid subid, TransactionId xid)
 {
- char tempdirpath[MAXPGPATH];
-
- TempTablespacePath(tempdirpath, DEFAULTTABLESPACE_OID);
-
- /*
- * We might need to create the tablespace's tempfile directory, if no
- * one has yet done so.
- */
- if ((MakePGDirectory(tempdirpath) < 0) && errno != EEXIST)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not create directory \"%s\": %m",
- tempdirpath)));
-
- snprintf(path, MAXPGPATH, "%s/%s%d-%u-%u.changes",
- tempdirpath, PG_TEMP_FILE_PREFIX, MyProcPid, subid, xid);
+ snprintf(path, MAXPGPATH, "%u-%u.changes", subid, xid);

Today, I was studying this change and its impact.  Initially, I
thought that because the patch has removed pgsql_tmp prefix from the
filename, it might create problems if the temporary files remain on
the disk after the crash.  Now as the patch has started using BufFile
interface, it seems to be internally taking care of the same by
generating names like
"base/pgsql_tmp/pgsql_tmp13774.0.sharedfileset/16393-513.changes.0".
Basically, it ensures to create the file in the directory starting
with pgsql_tmp.  I have tried by crashing the server in a situation
where the temp files remain and after the restart, they are removed.
So, it seems okay to generate file names like that but I still suggest
testing other paths like backup where we ignore files whose names
start with PG_TEMP_FILE_PREFIX.

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com