This opens the possibility to define keys for more types of statistics
kinds in PgStat_HashKey, the first case being 8-byte query IDs for
statistics like pg_stat_statements.
This increases the size of PgStat_HashKey from 12 to 16 bytes, while
PgStatShared_HashEntry, entry stored in the dshash for pgstats, keeps
the same size due to alignment.
xl_xact_stats_item, that tracks the stats items to drop in commit WAL
records, is increased from 12 to 16 bytes. Note that individual chunks
in commit WAL records should be multiples of sizeof(int), hence 8-byte
object IDs are stored as two uint32, based on a suggestion from Heikki
Linnakangas.
While on it, the field of PgStat_HashKey is renamed from "objoid" to
"objid", as for some stats kinds this field does not refer to OIDs but
just IDs, like for replication slot stats.
This commit bumps the following format variables:
- PGSTAT_FILE_FORMAT_ID, as PgStat_HashKey is written to the stats file
for non-serialized stats kinds in the dshash table.
- XLOG_PAGE_MAGIC for the changes in xl_xact_stats_item.
- Catalog version, for the SQL function pg_stat_have_stats().
Reviewed-by: Bertrand Drouvot
Discussion: https://postgr.es/m/ZsvTS9EW79Up8I62@paquier.xyz
Add WITHOUT OVERLAPS clause to PRIMARY KEY and UNIQUE constraints.
These are backed by GiST indexes instead of B-tree indexes, since they
are essentially exclusion constraints with = for the scalar parts of
the key and && for the temporal part.
(previously committed as 46a0cd4cef, reverted by 46a0cd4cefb; the new
part is this:)
Because 'empty' && 'empty' is false, the temporal PK/UQ constraint
allowed duplicates, which is confusing to users and breaks internal
expectations. For instance, when GROUP BY checks functional
dependencies on the PK, it allows selecting other columns from the
table, but in the presence of duplicate keys you could get the value
from any of their rows. So we need to forbid empties.
This all means that at the moment we can only support ranges and
multiranges for temporal PK/UQs, unlike the original patch (above).
Documentation and tests for this are added. But this could
conceivably be extended by introducing some more general support for
the notion of "empty" for other types.
Author: Paul A. Jungwirth <pj@illuminatedcomputing.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: jian he <jian.universality@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CA+renyUApHgSZF9-nd-a0+OPGharLQLO=mDHcY4_qQ0+noCUVg@mail.gmail.com
This is support function 12 for the GiST AM and translates
"well-known" RT*StrategyNumber values into whatever strategy number is
used by the opclass (since no particular numbers are actually
required). We will use this to support temporal PRIMARY
KEY/UNIQUE/FOREIGN KEY/FOR PORTION OF functionality.
This commit adds two implementations, one for internal GiST opclasses
(just an identity function) and another for btree_gist opclasses. It
updates btree_gist from 1.7 to 1.8, adding the support function for
all its opclasses.
(previously committed as 6db4598fcb, reverted by 8aee330af55; this is
essentially unchanged from those)
Author: Paul A. Jungwirth <pj@illuminatedcomputing.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: jian he <jian.universality@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CA+renyUApHgSZF9-nd-a0+OPGharLQLO=mDHcY4_qQ0+noCUVg@mail.gmail.com
This brings more clarity to heapam.c, by cleanly separating all the
logic related to WAL replay and the rest of Heap and Heap2, similarly
to other RMGRs like hash, btree, etc.
The header reorganization is also nice in heapam.c, cutting half of the
headers required.
Author: Li Yong
Reviewed-by: Sutou Kouhei, Michael Paquier
Discussion: https://postgr.es/m/EFE55E65-D7BD-4C6A-B630-91F43FD0771B@ebay.com
The only current implementation is for btree where it calls
_bt_getrootheight(). Other index types can now also use this to pass
information to their amcostestimate routine. Previously, btree was
hardcoded and other index types could not hook into the optimizer at
this point.
Author: Mark Dilger <mark.dilger@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/flat/E72EAA49-354D-4C2E-8EB9-255197F55330@enterprisedb.com
There was no need for these to be static buffers, local variables work
just as well. I think they were marked as 'static' to imply that they
are read-only, but 'const' is more appropriate for that, so change
them to const.
To make it possible to mark the variables as 'const', also add 'const'
decorations to the transformRelOptions() signature.
Reviewed-by: Andres Freund
Discussion: https://www.postgresql.org/message-id/54c29fb0-edf2-48ea-9814-44e918bbd6e8@iki.fi
When a standby is promoted, CleanupAfterArchiveRecovery() may decide
to rename the final WAL file from the old timeline by adding ".partial"
to the name. If WAL summarization is enabled and this file is renamed
before its partial contents are summarized, WAL summarization breaks:
the summarizer gets stuck at that point in the WAL stream and just
errors out.
To fix that, first make the startup process wait for WAL summarization
to catch up before renaming the file. Generally, this should be quick,
and if it's not, the user can shut off summarize_wal and try again.
To make this fix work, also teach the WAL summarizer that after a
promotion has occurred, no more WAL can appear on the previous
timeline: previously, the WAL summarizer wouldn't switch to the new
timeline until we actually started writing WAL there, but that meant
that when the startup process was waiting for the WAL summarizer, it
was waiting for an action that the summarizer wasn't yet prepared to
take.
In the process of fixing these bugs, I realized that the logic to wait
for WAL summarization to catch up was spread out in a way that made
it difficult to reuse properly, so this code refactors things to make
it easier.
Finally, add a test case that would have caught this bug and the
previously-fixed bug that WAL summarization sometimes needs to back up
when the timeline changes.
Discussion: https://postgr.es/m/CA+TgmoZGEsZodXC4f=XZNkAeyuDmWTSkpkjCEOcF19Am0mt_OA@mail.gmail.com
Previously, TidStoreIterateNext() would expand the set of offsets for
each block into an internal buffer that it overwrote each time. In
order to be able to collect the offsets for multiple blocks before
working with them, change the contract. Now, the offsets are obtained
by a separate call to TidStoreGetBlockOffsets(), which can be called at
a later time. TidStoreIteratorResult objects are safe to copy and store
in a queue.
Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/CAAKRu_bbkmwAzSBgnezancgJeXrQZXy4G4kBTd+5=cr86H5yew@mail.gmail.com
The two_phase option is controlled by both the publisher (as a slot
option) and the subscriber (as a subscription option), so the slot option
must also be modified.
Changing the 'two_phase' option for a subscription from 'true' to 'false'
is permitted only when there are no pending prepared transactions
corresponding to that subscription. Otherwise, the changes of already
prepared transactions can be replicated again along with their corresponding
commit leading to duplicate data or errors.
To avoid data loss, the 'two_phase' option for a subscription can only be
changed from 'false' to 'true' once the initial data synchronization is
completed. Therefore this is performed later by the logical replication worker.
Author: Hayato Kuroda, Ajin Cherian, Amit Kapila
Reviewed-by: Peter Smith, Hou Zhijie, Amit Kapila, Vitaly Davydov, Vignesh C
Discussion: https://postgr.es/m/8fab8-65d74c80-1-2f28e880@39088166
Add extern declarations in appropriate header files for global
variables related to GUC. In many cases, this was handled quite
inconsistently before, with some GUC variables declared in a header
file and some only pulled in via ad-hoc extern declarations in various
.c files.
Also add PGDLLIMPORT qualifications to those variables. These were
previously missing because src/tools/mark_pgdllimport.pl has only been
used with header files.
This also fixes -Wmissing-variable-declarations warnings for GUC
variables (not yet part of the standard warning options).
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://www.postgresql.org/message-id/flat/e0a62134-83da-4ba4-8cdb-ceb0111c95ce@eisentraut.org
slru.h described incorrectly how SLRU segment names are formatted
depending on the segment number and if long or short segment names are
used. This commit closes the gap with a better description, fitting
with the reality.
Reported-by: Noah Misch
Author: Aleksander Alekseev
Discussion: https://postgr.es/m/20240626002747.dc.nmisch@google.com
Backpatch-through: 17
To do this, we must include the wal_level in the first WAL record
covered by each summary file; so add wal_level to struct Checkpoint
and the payload of XLOG_CHECKPOINT_REDO and XLOG_END_OF_RECOVERY.
This, in turn, requires bumping XLOG_PAGE_MAGIC and, since the
Checkpoint is also stored in the control file, also
PG_CONTROL_VERSION. It's not great to do that so late in the release
cycle, but the alternative seems to ship v17 without robust
protections against this scenario, which could result in corrupted
incremental backups.
A side effect of this patch is that, when a server with
wal_level=replica is started with summarize_wal=on for the first time,
summarization will no longer begin with the oldest WAL that still
exists in pg_wal, but rather from the first checkpoint after that.
This change should be harmless, because a WAL summary for a partial
checkpoint cycle can never make an incremental backup possible when
it would otherwise not have been.
Report by Fujii Masao. Patch by me. Review and/or testing by Jakub
Wartak and Fujii Masao.
Discussion: http://postgr.es/m/6e30082e-041b-4e31-9633-95a66de76f5d@oss.nttdata.com
Reconstruction of an SP-GiST index by REINDEX CONCURRENTLY may
insert some REDIRECT tuples. This will typically happen in
a transaction that lacks an XID, which leads either to assertion
failure in spgFormDeadTuple or to insertion of a REDIRECT tuple
with zero xid. The latter's not good either, since eventually
VACUUM will apply GlobalVisTestIsRemovableXid() to the zero xid,
resulting in either an assertion failure or a garbage answer.
In practice, since REINDEX CONCURRENTLY locks out index scans
till it's done, it doesn't matter whether it inserts REDIRECTs
or PLACEHOLDERs; and likewise it doesn't matter how soon VACUUM
reduces such a REDIRECT to a PLACEHOLDER. So in non-assert builds
there's no observable problem here, other than perhaps a little
index bloat. But it's not behaving as intended.
To fix, remove the failing Assert in spgFormDeadTuple, acknowledging
that we might sometimes insert a zero XID; and guard VACUUM's
GlobalVisTestIsRemovableXid() call with a test for valid XID,
ensuring that we'll reduce such a REDIRECT the first time VACUUM
sees it. (Versions before v14 use TransactionIdPrecedes here,
which won't fail on zero xid, so they really have no bug at all
in non-assert builds.)
Another solution could be to not create REDIRECTs at all during
REINDEX CONCURRENTLY, making the relevant code paths treat that
case like index build (which likewise knows that no concurrent
index scans can be happening). That would allow restoring the
Assert in spgFormDeadTuple, but we'd still need the VACUUM change
because redirection tuples with zero xid may be out there already.
But there doesn't seem to be a nice way for spginsert() to tell that
it's being called in REINDEX CONCURRENTLY without some API changes,
so we'll leave that as a possible future improvement.
In HEAD, also rename the SpGistState.myXid field to redirectXid,
which seems less misleading (since it might not in fact be our
transaction's XID) and is certainly less uninformatively generic.
Per bug #18499 from Alexander Lakhin. Back-patch to all supported
branches.
Discussion: https://postgr.es/m/18499-8a519c280f956480@postgresql.org
Make sure that function declarations use names that exactly match the
corresponding names from function definitions in a few places. These
inconsistencies were all introduced during Postgres 17 development.
pg_bsd_indent still has a couple of similar inconsistencies, which I
(pgeoghegan) have left untouched for now.
This commit was written with help from clang-tidy, by mechanically
applying the same rules as similar clean-up commits (the earliest such
commit was commit 035ce1fe).
There were a few typedefs that were never used to define a variable or
field. This had the effect that the buildfarm's typedefs.list would
not include them, and so they would need to be re-added manually to
keep the overall pgindent result perfectly clean.
We can easily get rid of these typedefs to avoid the issue. In a few
cases, we just let the enum or struct stand on its own without a
typedef around it. In one case, an enum was abused to define flag
bits; that's better done with macro definitions.
This fixes all the remaining issues with missing entries in the
buildfarm's typedefs.list.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/1919000.1715815925@sss.pgh.pa.us
This feature set did not handle empty ranges correctly, and it's now
too late for PostgreSQL 17 to fix it.
The following commits are reverted:
6db4598fcb Add stratnum GiST support function
46a0cd4cef Add temporal PRIMARY KEY and UNIQUE constraints
86232a49a4 Fix comment on gist_stratnum_btree
030e10ff1a Rename pg_constraint.conwithoutoverlaps to conperiod
a88c800deb Use daterange and YMD in without_overlaps tests instead of tsrange.
5577a71fb0 Use half-open interval notation in without_overlaps tests
34768ee361 Add temporal FOREIGN KEY contraints
482e108cd3 Add test for REPLICA IDENTITY with a temporal key
c3db1f30cb doc: clarify PERIOD and WITHOUT OVERLAPS in CREATE TABLE
144c2ce0cc Fix ON CONFLICT DO NOTHING/UPDATE for temporal indexes
Discussion: https://www.postgresql.org/message-id/d0b64a7a-dfe4-4b84-a906-c7dedfa40a3e@eisentraut.org
The optimization for inserts into BRIN indexes added by c1ec02be1d
relies on a cache that needs to be explicitly released after calling
index_insert(). The commit however failed to invoke the cleanup in
validate_index(), which calls index_insert() indirectly through
table_index_validate_scan().
After inspecting index_insert() callers, it seems unique_key_recheck()
is missing the call too.
Fixed by adding the two missing index_insert_cleanup() calls.
The commit does two additional improvements. The aminsertcleanup()
signature is modified to have the index as the first argument, to make
it more like the other AM callbacks. And the aminsertcleanup() callback
is invoked even if the ii_AmCache is NULL, so that it can decide if the
cleanup is necessary.
Author: Alvaro Herrera, Tomas Vondra
Reported-by: Alexander Lakhin
Discussion: https://postgr.es/m/202401091043.e3nrqiad6gb7@alvherre.pgsql
This fixes various typos, duplicated words, and tiny bits of whitespace
mainly in code comments but also in docs.
Author: Daniel Gustafsson <daniel@yesql.se>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Alexander Lakhin <exclusion@gmail.com>
Author: David Rowley <dgrowleyml@gmail.com>
Author: Nazir Bilal Yavuz <byavuz81@gmail.com>
Discussion: https://postgr.es/m/3F577953-A29E-4722-98AD-2DA9EFF2CBB8@yesql.se
While keeping API the same, this commit provides a way for block-level table
AMs to re-use existing acquire_sample_rows() by providing custom callbacks
for getting the next block and the next tuple.
Reported-by: Andres Freund
Discussion: https://postgr.es/m/20240407214001.jgpg5q3yv33ve6y3%40awork3.anarazel.de
Reviewed-by: Pavel Borisov
Let table AM define custom reloptions for its tables. This allows specifying
AM-specific parameters by the WITH clause when creating a table.
The reloptions, which could be used outside of table AM, are now extracted
into the CommonRdOptions data structure. These options could be by decision
of table AM directly specified by a user or calculated in some way.
The new test module test_tam_options evaluates the ability to set up custom
reloptions and calculate fields of CommonRdOptions on their base.
The code may use some parts from prior work by Hao Wu.
Discussion: https://postgr.es/m/CAPpHfdurb9ycV8udYqM%3Do0sPS66PJ4RCBM1g-bBpvzUfogY0EA%40mail.gmail.com
Discussion: https://postgr.es/m/AMUA1wBBBxfc3tKRLLdU64rb.1.1683276279979.Hmail.wuhao%40hashdata.cn
Reviewed-by: Reviewed-by: Pavel Borisov, Matthias van de Meent, Jess Davis
The ANALYZE command prefetches and reads sample blocks chosen by a
BlockSampler algorithm. Instead of calling [Prefetch|Read]Buffer() for
each block, ANALYZE now uses the streaming API introduced in b5a9b18cd0.
Author: Nazir Bilal Yavuz <byavuz81@gmail.com>
Reviewed-by: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Jakub Wartak <jakub.wartak@enterprisedb.com>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/flat/CAN55FZ0UhXqk9v3y-zW_fp4-WCp43V8y0A72xPmLkOM%2B6M%2BmJg%40mail.gmail.com
Commit 7c70996ebf introduced an optimization to allow bitmap
scans to operate like index-only scans by not fetching a block from the
heap if none of the underlying data is needed and the block is marked
all visible in the visibility map.
With the introduction of table AMs, a FIXME was added to this code
indicating that the skip_fetch logic should be pushed into the table
AM-specific code, as not all table AMs may use a visibility map in the
same way.
This commit resolves this FIXME for the current block. The layering
violation is still present in BitmapHeapScans's prefetching code, which
uses the visibility map to decide whether or not to prefetch a block.
However, this can be addressed independently.
Author: Melanie Plageman
Reviewed-by: Andres Freund, Heikki Linnakangas, Tomas Vondra, Mark Dilger
Discussion: https://postgr.es/m/CAAKRu_ZwCwWFeL_H3ia26bP2e7HiKLWt0ZmGXPVwPO6uXq0vaA%40mail.gmail.com
Commit 9e8da0f7 taught nbtree to handle ScalarArrayOpExpr quals
natively. This works by pushing down the full context (the array keys)
to the nbtree index AM, enabling it to execute multiple primitive index
scans that the planner treats as one continuous index scan/index path.
This earlier enhancement enabled nbtree ScalarArrayOp index-only scans.
It also allowed scans with ScalarArrayOp quals to return ordered results
(with some notable restrictions, described further down).
Take this general approach a lot further: teach nbtree SAOP index scans
to decide how to execute ScalarArrayOp scans (when and where to start
the next primitive index scan) based on physical index characteristics.
This can be far more efficient. All SAOP scans will now reliably avoid
duplicative leaf page accesses (just like any other nbtree index scan).
SAOP scans whose array keys are naturally clustered together now require
far fewer index descents, since we'll reliably avoid starting a new
primitive scan just to get to a later offset from the same leaf page.
The scan's arrays now advance using binary searches for the array
element that best matches the next tuple's attribute value. Required
scan key arrays (i.e. arrays from scan keys that can terminate the scan)
ratchet forward in lockstep with the index scan. Non-required arrays
(i.e. arrays from scan keys that can only exclude non-matching tuples)
"advance" without the process ever rolling over to a higher-order array.
Naturally, only required SAOP scan keys trigger skipping over leaf pages
(non-required arrays cannot safely end or start primitive index scans).
Consequently, even index scans of a composite index with a high-order
inequality scan key (which we'll mark required) and a low-order SAOP
scan key (which we won't mark required) now avoid repeating leaf page
accesses -- that benefit isn't limited to simpler equality-only cases.
In general, all nbtree index scans now output tuples as if they were one
continuous index scan -- even scans that mix a high-order inequality
with lower-order SAOP equalities reliably output tuples in index order.
This allows us to remove a couple of special cases that were applied
when building index paths with SAOP clauses during planning.
Bugfix commit 807a40c5 taught the planner to avoid generating unsafe
path keys: path keys on a multicolumn index path, with a SAOP clause on
any attribute beyond the first/most significant attribute. These cases
are now all safe, so we go back to generating path keys without regard
for the presence of SAOP clauses (just like with any other clause type).
Affected queries can now exploit scan output order in all the usual ways
(e.g., certain "ORDER BY ... LIMIT n" queries can now terminate early).
Also undo changes from follow-up bugfix commit a4523c5a, which taught
the planner to produce alternative index paths, with path keys, but
without low-order SAOP index quals (filter quals were used instead).
We'll no longer generate these alternative paths, since they can no
longer offer any meaningful advantages over standard index qual paths.
Affected queries thereby avoid all of the disadvantages that come from
using filter quals within index scan nodes. They can avoid extra heap
page accesses from using filter quals to exclude non-matching tuples
(index quals will never have that problem). They can also skip over
irrelevant sections of the index in more cases (though only when nbtree
determines that starting another primitive scan actually makes sense).
There is a theoretical risk that removing restrictions on SAOP index
paths from the planner will break compatibility with amcanorder-based
index AMs maintained as extensions. Such an index AM could have the
same limitations around ordered SAOP scans as nbtree had up until now.
Adding a pro forma incompatibility item about the issue to the Postgres
17 release notes seems like a good idea.
Author: Peter Geoghegan <pg@bowt.ie>
Author: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reviewed-By: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/CAH2-Wz=ksvN_sjcnD1+Bt-WtifRA5ok48aDYnq3pkKhxgMQpcw@mail.gmail.com
To allow the use of the read stream API added in b5a9b18cd for
sequential scans on heap tables, here we make some adjustments to make
that change less invasive and perhaps make the code easier to follow in
the process.
Here heapgetpage() gets broken into two functions:
1) The part which reads the block has now been moved into a function
named heapfetchbuf().
2) The part which performed pruning and populated the scan's
rs_vistuples[] array is now moved into a new function named
heap_prepare_pagescan().
The functionality provided by heap_prepare_pagescan() was only ever
required by SO_ALLOW_PAGEMODE scans, so the branching that was
previously done in heapgetpage() is no longer needed as we simply just
don't call heap_prepare_pagescan() from heapgettup() in the refactored
code.
Author: Melanie Plageman
Discussion: https://postgr.es/m/CAAKRu_YtXJiYKQvb5JsA2SkwrsizYLugs4sSOZh3EAjKUg=gEQ@mail.gmail.com
Execute both freezing and pruning of tuples in the same
heap_page_prune() function, now called heap_page_prune_and_freeze(),
and emit a single WAL record containing all changes. That reduces the
overall amount of WAL generated.
This moves the freezing logic from vacuumlazy.c to the
heap_page_prune_and_freeze() function. The main difference in the
coding is that in vacuumlazy.c, we looked at the tuples after the
pruning had already happened, but in heap_page_prune_and_freeze() we
operate on the tuples before pruning. The heap_prepare_freeze_tuple()
function is now invoked after we have determined that a tuple is not
going to be pruned away.
VACUUM no longer needs to loop through the items on the page after
pruning. heap_page_prune_and_freeze() does all the work. It now
returns the list of dead offsets, including existing LP_DEAD items, to
the caller. Similarly it's now responsible for tracking 'all_visible',
'all_frozen', and 'hastup' on the caller's behalf.
Author: Melanie Plageman <melanieplageman@gmail.com>
Discussion: https://www.postgresql.org/message-id/20240330055710.kqg6ii2cdojsxgje@liskov
Currently there is only one option, HEAP_PAGE_PRUNE_MARK_UNUSED_NOW
which replaces the old boolean argument, but upcoming patches will
introduce at least one more. Having a lot of boolean arguments makes
it hard to see at the call sites what the arguments mean, so prefer a
bitmask of options with human-readable names.
Author: Melanie Plageman <melanieplageman@gmail.com>
Author: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Discussion: https://www.postgresql.org/message-id/20240401172219.fngjosaqdgqqvg4e@liskov
Previously, the executor did index insert unconditionally after calling
table AM interface methods tuple_insert() and multi_insert(). This commit
introduces the new parameter insert_indexes for these two methods. Setting
'*insert_indexes' to true saves the current logic. Setting it to false
indicates that table AM cares about index inserts itself and doesn't want the
caller to do that.
Discussion: https://postgr.es/m/CAPpHfdurb9ycV8udYqM%3Do0sPS66PJ4RCBM1g-bBpvzUfogY0EA%40mail.gmail.com
Reviewed-by: Pavel Borisov, Matthias van de Meent, Mark Dilger
Currently, there is just one algorithm for sampling tuples from a table written
in acquire_sample_rows(). Custom table AM can just redefine the way to get the
next block/tuple by implementing scan_analyze_next_block() and
scan_analyze_next_tuple() API functions.
This approach doesn't seem general enough. For instance, it's unclear how to
sample this way index-organized tables. This commit allows table AM to
encapsulate the whole sampling algorithm (currently implemented in
acquire_sample_rows()) into the relation_analyze() API function.
Discussion: https://postgr.es/m/CAPpHfdurb9ycV8udYqM%3Do0sPS66PJ4RCBM1g-bBpvzUfogY0EA%40mail.gmail.com
Reviewed-by: Pavel Borisov, Matthias van de Meent
Previously, the behavior of TidStoreCreate() was inconsistent between
local and shared TidStore instances in terms of memory limitation. For
local TidStore, a memory context was created with initial and maximum
memory block sizes, as well as a minimum memory context size, based on
the specified max_bytes values. However, for shared TidStore, the
provided DSA area was used for TID storage. Although commit bb952c8c8b
allowed specifying the initial and maximum DSA segment sizes, callers
would have needed to clamp their own limits, which was not consistent
and user-friendly.
With this commit, when creating a shared TidStore, a dedicated DSA
area is created for TID storage instead of using a provided DSA
area. The initial and maximum DSA segment sizes are chosen based on
the specified max_bytes. Other processes can attach to the shared
TidStore using the handle of the created DSA returned by the new
TidStoreGetDSA() function and the DSA pointer returned by
TidStoreGetHandle(). The created DSA has the same lifetime as the
shared TidStore and is deleted when all processes detach from it.
To improve clarity, the TidStoreCreate() function has been divided
into two separate functions: TidStoreCreateLocal() and
TidStoreCreateShared().
Reviewed-by: John Naylor
Discussion: https://postgr.es/m/CAD21AoAyc1j%3DBCdUqZfk6qbdjZ68UgRx1Gkpk0oah4K7S0Ri9g%40mail.gmail.com
Michael Paquier