From 6cae9d2c10e151f741e7bc64a8b70bb2615c367c Mon Sep 17 00:00:00 2001 From: Alexander Korotkov Date: Thu, 19 Sep 2019 21:30:19 +0300 Subject: Improve handling of NULLs in KNN-GiST and KNN-SP-GiST This commit improves subject in two ways: * It removes ugliness of 02f90879e7, which stores distance values and null flags in two separate arrays after GISTSearchItem struct. Instead we pack both distance value and null flag in IndexOrderByDistance struct. Alignment overhead should be negligible, because we typically deal with at most few "col op const" expressions in ORDER BY clause. * It fixes handling of "col op NULL" expression in KNN-SP-GiST. Now, these expression are not passed to support functions, which can't deal with them. Instead, NULL result is implicitly assumed. It future we may decide to teach support functions to deal with NULL arguments, but current solution is bugfix suitable for backpatch. Reported-by: Nikita Glukhov Discussion: https://postgr.es/m/826f57ee-afc7-8977-c44c-6111d18b02ec%40postgrespro.ru Author: Nikita Glukhov Reviewed-by: Alexander Korotkov Backpatch-through: 9.4 --- src/backend/access/gist/gistget.c | 68 ++++++++++++++------------------------- 1 file changed, 24 insertions(+), 44 deletions(-) (limited to 'src/backend/access/gist/gistget.c') diff --git a/src/backend/access/gist/gistget.c b/src/backend/access/gist/gistget.c index db633a9475..22d790d822 100644 --- a/src/backend/access/gist/gistget.c +++ b/src/backend/access/gist/gistget.c @@ -112,9 +112,8 @@ gistkillitems(IndexScanDesc scan) * Similarly, *recheck_distances_p is set to indicate whether the distances * need to be rechecked, and it is also ignored for non-leaf entries. * - * If we are doing an ordered scan, so->distancesValues[] and - * so->distancesNulls[] is filled with distance data from the distance() - * functions before returning success. + * If we are doing an ordered scan, so->distances[] is filled with distance + * data from the distance() functions before returning success. * * We must decompress the key in the IndexTuple before passing it to the * sk_funcs (which actually are the opclass Consistent or Distance methods). @@ -135,8 +134,7 @@ gistindex_keytest(IndexScanDesc scan, GISTSTATE *giststate = so->giststate; ScanKey key = scan->keyData; int keySize = scan->numberOfKeys; - double *distance_value_p; - bool *distance_null_p; + IndexOrderByDistance *distance_p; Relation r = scan->indexRelation; *recheck_p = false; @@ -155,8 +153,8 @@ gistindex_keytest(IndexScanDesc scan, elog(ERROR, "invalid GiST tuple found on leaf page"); for (i = 0; i < scan->numberOfOrderBys; i++) { - so->distanceValues[i] = -get_float8_infinity(); - so->distanceNulls[i] = false; + so->distances[i].value = -get_float8_infinity(); + so->distances[i].isnull = false; } return true; } @@ -240,8 +238,7 @@ gistindex_keytest(IndexScanDesc scan, /* OK, it passes --- now let's compute the distances */ key = scan->orderByData; - distance_value_p = so->distanceValues; - distance_null_p = so->distanceNulls; + distance_p = so->distances; keySize = scan->numberOfOrderBys; while (keySize > 0) { @@ -256,8 +253,8 @@ gistindex_keytest(IndexScanDesc scan, if ((key->sk_flags & SK_ISNULL) || isNull) { /* Assume distance computes as null */ - *distance_value_p = 0.0; - *distance_null_p = true; + distance_p->value = 0.0; + distance_p->isnull = true; } else { @@ -294,13 +291,12 @@ gistindex_keytest(IndexScanDesc scan, ObjectIdGetDatum(key->sk_subtype), PointerGetDatum(&recheck)); *recheck_distances_p |= recheck; - *distance_value_p = DatumGetFloat8(dist); - *distance_null_p = false; + distance_p->value = DatumGetFloat8(dist); + distance_p->isnull = false; } key++; - distance_value_p++; - distance_null_p++; + distance_p++; keySize--; } @@ -313,8 +309,7 @@ gistindex_keytest(IndexScanDesc scan, * * scan: index scan we are executing * pageItem: search queue item identifying an index page to scan - * myDistanceValues: distances array associated with pageItem, or NULL at the root - * myDistanceNulls: null flags for myDistanceValues array, or NULL at the root + * myDistances: distances array associated with pageItem, or NULL at the root * tbm: if not NULL, gistgetbitmap's output bitmap * ntids: if not NULL, gistgetbitmap's output tuple counter * @@ -332,8 +327,7 @@ gistindex_keytest(IndexScanDesc scan, */ static void gistScanPage(IndexScanDesc scan, GISTSearchItem *pageItem, - double *myDistanceValues, bool *myDistanceNulls, - TIDBitmap *tbm, int64 *ntids) + IndexOrderByDistance *myDistances, TIDBitmap *tbm, int64 *ntids) { GISTScanOpaque so = (GISTScanOpaque) scan->opaque; GISTSTATE *giststate = so->giststate; @@ -370,7 +364,7 @@ gistScanPage(IndexScanDesc scan, GISTSearchItem *pageItem, GISTSearchItem *item; /* This can't happen when starting at the root */ - Assert(myDistanceValues != NULL && myDistanceNulls != NULL); + Assert(myDistances != NULL); oldcxt = MemoryContextSwitchTo(so->queueCxt); @@ -380,10 +374,8 @@ gistScanPage(IndexScanDesc scan, GISTSearchItem *pageItem, item->data.parentlsn = pageItem->data.parentlsn; /* Insert it into the queue using same distances as for this page */ - memcpy(GISTSearchItemDistanceValues(item, scan->numberOfOrderBys), - myDistanceValues, sizeof(double) * scan->numberOfOrderBys); - memcpy(GISTSearchItemDistanceNulls(item, scan->numberOfOrderBys), - myDistanceNulls, sizeof(bool) * scan->numberOfOrderBys); + memcpy(item->distances, myDistances, + sizeof(item->distances[0]) * scan->numberOfOrderBys); pairingheap_add(so->queue, &item->phNode); @@ -527,10 +519,8 @@ gistScanPage(IndexScanDesc scan, GISTSearchItem *pageItem, } /* Insert it into the queue using new distance data */ - memcpy(GISTSearchItemDistanceValues(item, nOrderBys), - so->distanceValues, sizeof(double) * nOrderBys); - memcpy(GISTSearchItemDistanceNulls(item, nOrderBys), - so->distanceNulls, sizeof(bool) * nOrderBys); + memcpy(item->distances, so->distances, + sizeof(item->distances[0]) * nOrderBys); pairingheap_add(so->queue, &item->phNode); @@ -595,8 +585,7 @@ getNextNearest(IndexScanDesc scan) scan->xs_recheck = item->data.heap.recheck; index_store_float8_orderby_distances(scan, so->orderByTypes, - GISTSearchItemDistanceValues(item, scan->numberOfOrderBys), - GISTSearchItemDistanceNulls(item, scan->numberOfOrderBys), + item->distances, item->data.heap.recheckDistances); /* in an index-only scan, also return the reconstructed tuple. */ @@ -609,10 +598,7 @@ getNextNearest(IndexScanDesc scan) /* visit an index page, extract its items into queue */ CHECK_FOR_INTERRUPTS(); - gistScanPage(scan, item, - GISTSearchItemDistanceValues(item, scan->numberOfOrderBys), - GISTSearchItemDistanceNulls(item, scan->numberOfOrderBys), - NULL, NULL); + gistScanPage(scan, item, item->distances, NULL, NULL); } pfree(item); @@ -650,7 +636,7 @@ gistgettuple(IndexScanDesc scan, ScanDirection dir) fakeItem.blkno = GIST_ROOT_BLKNO; memset(&fakeItem.data.parentlsn, 0, sizeof(GistNSN)); - gistScanPage(scan, &fakeItem, NULL, NULL, NULL, NULL); + gistScanPage(scan, &fakeItem, NULL, NULL, NULL); } if (scan->numberOfOrderBys > 0) @@ -744,10 +730,7 @@ gistgettuple(IndexScanDesc scan, ScanDirection dir) * this page, we fall out of the inner "do" and loop around to * return them. */ - gistScanPage(scan, item, - GISTSearchItemDistanceValues(item, scan->numberOfOrderBys), - GISTSearchItemDistanceNulls(item, scan->numberOfOrderBys), - NULL, NULL); + gistScanPage(scan, item, item->distances, NULL, NULL); pfree(item); } while (so->nPageData == 0); @@ -778,7 +761,7 @@ gistgetbitmap(IndexScanDesc scan, TIDBitmap *tbm) fakeItem.blkno = GIST_ROOT_BLKNO; memset(&fakeItem.data.parentlsn, 0, sizeof(GistNSN)); - gistScanPage(scan, &fakeItem, NULL, NULL, tbm, &ntids); + gistScanPage(scan, &fakeItem, NULL, tbm, &ntids); /* * While scanning a leaf page, ItemPointers of matching heap tuples will @@ -793,10 +776,7 @@ gistgetbitmap(IndexScanDesc scan, TIDBitmap *tbm) CHECK_FOR_INTERRUPTS(); - gistScanPage(scan, item, - GISTSearchItemDistanceValues(item, scan->numberOfOrderBys), - GISTSearchItemDistanceNulls(item, scan->numberOfOrderBys), - tbm, &ntids); + gistScanPage(scan, item, item->distances, tbm, &ntids); pfree(item); } -- cgit v1.2.1