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[PATCH 5/8] Optimize allocations in bringetbitmap 2+ messages / 2 participants [nested] [flat]
* [PATCH 5/8] Optimize allocations in bringetbitmap @ 2021-03-02 18:57 Tomas Vondra <[email protected]> 0 siblings, 0 replies; 2+ messages in thread From: Tomas Vondra @ 2021-03-02 18:57 UTC (permalink / raw) The bringetbitmap function allocates memory for various purposes, which may be quite expensive, depending on the number of scan keys. Instead of allocating them separately, allocate one bit chunk of memory an carve it into smaller pieces as needed - all the pieces have the same lifespan, and it saves quite a bit of CPU and memory overhead. Author: Tomas Vondra <[email protected]> Discussion: https://postgr.es/m/[email protected] --- src/backend/access/brin/brin.c | 60 ++++++++++++++++++++++++++-------- 1 file changed, 47 insertions(+), 13 deletions(-) diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c index 9f2656b8d9..1f82e965f9 100644 --- a/src/backend/access/brin/brin.c +++ b/src/backend/access/brin/brin.c @@ -373,6 +373,9 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm) int *nkeys, *nnullkeys; int keyno; + char *ptr; + Size len; + char *tmp PG_USED_FOR_ASSERTS_ONLY; opaque = (BrinOpaque *) scan->opaque; bdesc = opaque->bo_bdesc; @@ -402,15 +405,52 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm) * We keep null and regular keys separate, so that we can pass just the * regular keys to the consistent function easily. * + * To reduce the allocation overhead, we allocate one big chunk and then + * carve it into smaller arrays ourselves. All the pieces have exactly the + * same lifetime, so that's OK. + * * XXX The widest table can have ~1600 attributes, so this may allocate a * couple kilobytes of memory). We could invent a more compact approach * (with just space for used attributes) but that would make the matching * more complicated, so it may not be a win. */ - keys = palloc0(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts); - nullkeys = palloc0(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts); - nkeys = palloc0(sizeof(int) * bdesc->bd_tupdesc->natts); - nnullkeys = palloc0(sizeof(int) * bdesc->bd_tupdesc->natts); + len = + MAXALIGN(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts) + /* regular keys */ + MAXALIGN(sizeof(ScanKey) * scan->numberOfKeys) * bdesc->bd_tupdesc->natts + + MAXALIGN(sizeof(int) * bdesc->bd_tupdesc->natts) + + MAXALIGN(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts) + /* NULL keys */ + MAXALIGN(sizeof(ScanKey) * scan->numberOfKeys) * bdesc->bd_tupdesc->natts + + MAXALIGN(sizeof(int) * bdesc->bd_tupdesc->natts); + + ptr = palloc(len); + tmp = ptr; + + keys = (ScanKey **) ptr; + ptr += MAXALIGN(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts); + + nullkeys = (ScanKey **) ptr; + ptr += MAXALIGN(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts); + + nkeys = (int *) ptr; + ptr += MAXALIGN(sizeof(int) * bdesc->bd_tupdesc->natts); + + nnullkeys = (int *) ptr; + ptr += MAXALIGN(sizeof(int) * bdesc->bd_tupdesc->natts); + + for (int i = 0; i < bdesc->bd_tupdesc->natts; i++) + { + keys[i] = (ScanKey *) ptr; + ptr += MAXALIGN(sizeof(ScanKey) * scan->numberOfKeys); + + nullkeys[i] = (ScanKey *) ptr; + ptr += MAXALIGN(sizeof(ScanKey) * scan->numberOfKeys); + } + + Assert(tmp + len == ptr); + + /* zero the number of keys */ + memset(nkeys, 0, sizeof(int) * bdesc->bd_tupdesc->natts); + memset(nnullkeys, 0, sizeof(int) * bdesc->bd_tupdesc->natts); /* * Preprocess the scan keys - split them into per-attribute arrays. @@ -444,9 +484,9 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm) { FmgrInfo *tmp; - /* No key/null arrays for this attribute. */ - Assert((keys[keyattno - 1] == NULL) && (nkeys[keyattno - 1] == 0)); - Assert((nullkeys[keyattno - 1] == NULL) && (nnullkeys[keyattno - 1] == 0)); + /* First time we see this attribute, so no key/null keys. */ + Assert(nkeys[keyattno - 1] == 0); + Assert(nnullkeys[keyattno - 1] == 0); tmp = index_getprocinfo(idxRel, keyattno, BRIN_PROCNUM_CONSISTENT); @@ -457,17 +497,11 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm) /* Add key to the proper per-attribute array. */ if (key->sk_flags & SK_ISNULL) { - if (!nullkeys[keyattno - 1]) - nullkeys[keyattno - 1] = palloc0(sizeof(ScanKey) * scan->numberOfKeys); - nullkeys[keyattno - 1][nnullkeys[keyattno - 1]] = key; nnullkeys[keyattno - 1]++; } else { - if (!keys[keyattno - 1]) - keys[keyattno - 1] = palloc0(sizeof(ScanKey) * scan->numberOfKeys); - keys[keyattno - 1][nkeys[keyattno - 1]] = key; nkeys[keyattno - 1]++; } -- 2.26.2 --------------556A1DC61262AF15641DB204 Content-Type: text/x-patch; charset=UTF-8; name="0006-BRIN-bloom-indexes-20210308b.patch" Content-Transfer-Encoding: 8bit Content-Disposition: attachment; filename="0006-BRIN-bloom-indexes-20210308b.patch" ^ permalink raw reply [nested|flat] 2+ messages in thread
* [PATCH v19 3/6] Refactor index_concurrently_create_copy() for use with REPACK (CONCURRENTLY). @ 2025-08-11 13:31 Antonin Houska <[email protected]> 0 siblings, 0 replies; 2+ messages in thread From: Antonin Houska @ 2025-08-11 13:31 UTC (permalink / raw) This patch moves the code to index_create_copy() and adds a "concurrently" parameter so it can be used by REPACK (CONCURRENTLY). With the CONCURRENTLY option, REPACK cannot simply swap the heap file and rebuild its indexes. Instead, it needs to build a separate set of indexes (including system catalog entries) *before* the actual swap, to reduce the time AccessExclusiveLock needs to be held for. --- src/backend/catalog/index.c | 36 ++++++++++++++++++++++++++++-------- src/include/catalog/index.h | 3 +++ 2 files changed, 31 insertions(+), 8 deletions(-) diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 3063abff9a5..0dee1b1a9d8 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1290,15 +1290,31 @@ index_create(Relation heapRelation, /* * index_concurrently_create_copy * - * Create concurrently an index based on the definition of the one provided by - * caller. The index is inserted into catalogs and needs to be built later - * on. This is called during concurrent reindex processing. - * - * "tablespaceOid" is the tablespace to use for this index. + * Variant of index_create_copy(), called during concurrent reindex + * processing. */ Oid index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId, Oid tablespaceOid, const char *newName) +{ + return index_create_copy(heapRelation, oldIndexId, tablespaceOid, newName, + true); +} + +/* + * index_create_copy + * + * Create an index based on the definition of the one provided by caller. The + * index is inserted into catalogs and needs to be built later on. + * + * "tablespaceOid" is the tablespace to use for this index. + * + * The actual implementation of index_concurrently_create_copy(), reusable for + * other purposes. + */ +Oid +index_create_copy(Relation heapRelation, Oid oldIndexId, Oid tablespaceOid, + const char *newName, bool concurrently) { Relation indexRelation; IndexInfo *oldInfo, @@ -1317,6 +1333,7 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId, List *indexColNames = NIL; List *indexExprs = NIL; List *indexPreds = NIL; + int flags = 0; indexRelation = index_open(oldIndexId, RowExclusiveLock); @@ -1325,9 +1342,9 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId, /* * Concurrent build of an index with exclusion constraints is not - * supported. + * supported. If !concurrently, ii_ExclusinOps is currently not needed. */ - if (oldInfo->ii_ExclusionOps != NULL) + if (oldInfo->ii_ExclusionOps != NULL && concurrently) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("concurrent index creation for exclusion constraints is not supported"))); @@ -1435,6 +1452,9 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId, stattargets[i].isnull = isnull; } + if (concurrently) + flags = INDEX_CREATE_SKIP_BUILD | INDEX_CREATE_CONCURRENT; + /* * Now create the new index. * @@ -1458,7 +1478,7 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId, indcoloptions->values, stattargets, reloptionsDatum, - INDEX_CREATE_SKIP_BUILD | INDEX_CREATE_CONCURRENT, + flags, 0, true, /* allow table to be a system catalog? */ false, /* is_internal? */ diff --git a/src/include/catalog/index.h b/src/include/catalog/index.h index 4daa8bef5ee..063a891351a 100644 --- a/src/include/catalog/index.h +++ b/src/include/catalog/index.h @@ -99,6 +99,9 @@ extern Oid index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId, Oid tablespaceOid, const char *newName); +extern Oid index_create_copy(Relation heapRelation, Oid oldIndexId, + Oid tablespaceOid, const char *newName, + bool concurrently); extern void index_concurrently_build(Oid heapRelationId, Oid indexRelationId); -- 2.39.5 --ipmcfwv2cm3fpxaf Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v19-0004-Move-conversion-of-a-historic-to-MVCC-snapshot-t.patch" ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2025-08-11 13:31 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2021-03-02 18:57 [PATCH 5/8] Optimize allocations in bringetbitmap Tomas Vondra <[email protected]> 2025-08-11 13:31 [PATCH v19 3/6] Refactor index_concurrently_create_copy() for use with REPACK (CONCURRENTLY). Antonin Houska <[email protected]>
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