14 Commits (6baa17fbd1a76cd4056168fa718b7e7fd65748ec)

Author	SHA1	Message	Date
Alexander Korotkov	911e702077	Implement operator class parameters ... PostgreSQL provides set of template index access methods, where opclasses have much freedom in the semantics of indexing. These index AMs are GiST, GIN, SP-GiST and BRIN. There opclasses define representation of keys, operations on them and supported search strategies. So, it's natural that opclasses may be faced some tradeoffs, which require user-side decision. This commit implements opclass parameters allowing users to set some values, which tell opclass how to index the particular dataset. This commit doesn't introduce new storage in system catalog. Instead it uses pg_attribute.attoptions, which is used for table column storage options but unused for index attributes. In order to evade changing signature of each opclass support function, we implement unified way to pass options to opclass support functions. Options are set to fn_expr as the constant bytea expression. It's possible due to the fact that opclass support functions are executed outside of expressions, so fn_expr is unused for them. This commit comes with some examples of opclass options usage. We parametrize signature length in GiST. That applies to multiple opclasses: tsvector_ops, gist__intbig_ops, gist_ltree_ops, gist__ltree_ops, gist_trgm_ops and gist_hstore_ops. Also we parametrize maximum number of integer ranges for gist__int_ops. However, the main future usage of this feature is expected to be json, where users would be able to specify which way to index particular json parts. Catversion is bumped. Discussion: https://postgr.es/m/d22c3a18-31c7-1879-fc11-4c1ce2f5e5af%40postgrespro.ru Author: Nikita Glukhov, revised by me Reviwed-by: Nikolay Shaplov, Robert Haas, Tom Lane, Tomas Vondra, Alvaro Herrera	6 years ago
Peter Geoghegan	0d861bbb70	Add deduplication to nbtree. ... Deduplication reduces the storage overhead of duplicates in indexes that use the standard nbtree index access method. The deduplication process is applied lazily, after the point where opportunistic deletion of LP_DEAD-marked index tuples occurs. Deduplication is only applied at the point where a leaf page split would otherwise be required. New posting list tuples are formed by merging together existing duplicate tuples. The physical representation of the items on an nbtree leaf page is made more space efficient by deduplication, but the logical contents of the page are not changed. Even unique indexes make use of deduplication as a way of controlling bloat from duplicates whose TIDs point to different versions of the same logical table row. The lazy approach taken by nbtree has significant advantages over a GIN style eager approach. Most individual inserts of index tuples have exactly the same overhead as before. The extra overhead of deduplication is amortized across insertions, just like the overhead of page splits. The key space of indexes works in the same way as it has since commit dd299df8 (the commit that made heap TID a tiebreaker column). Testing has shown that nbtree deduplication can generally make indexes with about 10 or 15 tuples for each distinct key value about 2.5X - 4X smaller, even with single column integer indexes (e.g., an index on a referencing column that accompanies a foreign key). The final size of single column nbtree indexes comes close to the final size of a similar contrib/btree_gin index, at least in cases where GIN's posting list compression isn't very effective. This can significantly improve transaction throughput, and significantly reduce the cost of vacuuming indexes. A new index storage parameter (deduplicate_items) controls the use of deduplication. The default setting is 'on', so all new B-Tree indexes automatically use deduplication where possible. This decision will be reviewed at the end of the Postgres 13 beta period. There is a regression of approximately 2% of transaction throughput with synthetic workloads that consist of append-only inserts into a table with several non-unique indexes, where all indexes have few or no repeated values. The underlying issue is that cycles are wasted on unsuccessful attempts at deduplicating items in non-unique indexes. There doesn't seem to be a way around it short of disabling deduplication entirely. Note that deduplication of items in unique indexes is fairly well targeted in general, which avoids the problem there (we can use a special heuristic to trigger deduplication passes in unique indexes, since we're specifically targeting "version bloat"). Bump XLOG_PAGE_MAGIC because xl_btree_vacuum changed. No bump in BTREE_VERSION, since the representation of posting list tuples works in a way that's backwards compatible with version 4 indexes (i.e. indexes built on PostgreSQL 12). However, users must still REINDEX a pg_upgrade'd index to use deduplication, regardless of the Postgres version they've upgraded from. This is the only way to set the new nbtree metapage flag indicating that deduplication is generally safe. Author: Anastasia Lubennikova, Peter Geoghegan Reviewed-By: Peter Geoghegan, Heikki Linnakangas Discussion: https://postgr.es/m/55E4051B.7020209@postgrespro.ru https://postgr.es/m/4ab6e2db-bcee-f4cf-0916-3a06e6ccbb55@postgrespro.ru	6 years ago
Tom Lane	b3c265d7be	Fix corner-case failure in match_pattern_prefix(). ... The planner's optimization code for LIKE and regex operators could error out with a complaint like "no = operator for opfamily NNN" if someone created a binary-compatible index (for example, a bpchar_ops index on a text column) on the LIKE's left argument. This is a consequence of careless refactoring in commit 74dfe58a5. The old code in match_special_index_operator only accepted specific combinations of the pattern operator and the index opclass, thereby indirectly guaranteeing that the opclass would have a comparison operator with the same LHS input type as the pattern operator. While moving the logic out to a planner support function, I simplified that test in a way that no longer guarantees that. Really though we'd like an altogether weaker dependency on the opclass, so rather than put back exactly the old code, just allow lookup failure. I have in mind now to rewrite this logic completely, but this is the minimum change needed to fix the bug in v12. Per report from Manuel Rigger. Back-patch to v12 where the mistake came in. Discussion: https://postgr.es/m/CA+u7OA7nnGYy8rY0vdTe811NuA+Frr9nbcBO9u2Z+JxqNaud+g@mail.gmail.com	6 years ago
Tom Lane	385d396b80	Split up a couple of long-running regression test scripts. ... The point of this change is to increase the potential for parallelism while running the core regression tests. Most people these days are using parallel testing modes on multi-core machines, so we might as well try a bit harder to keep multiple cores busy. Hence, a test that runs much longer than others in its parallel group is a candidate to be sub-divided. In this patch, create_index.sql and join.sql are split up. I haven't changed the content of the tests in any way, just moved them. I moved create_index.sql's SP-GiST-related tests into a new script create_index_spgist, and moved its btree multilevel page deletion test over to the existing script btree_index. (btree_index is a more natural home for that test, and it's shorter than others in its parallel group, so this doesn't hurt total runtime of that group.) There might be room for more aggressive splitting of create_index, but this is enough to improve matters considerably. Likewise, I moved join.sql's "exercises for the hash join code" into a new file join_hash. Those exercises contributed three-quarters of the script's runtime. Which might well be excessive ... but for the moment, I'm satisfied with shoving them into a different parallel group, where they can share runtime with the roughly-equally-lengthy gist test. (Note for anybody following along at home: there are interesting interactions between the runtimes of create_index and anything running in parallel with it, because the tests of CREATE INDEX CONCURRENTLY in that file will repeatedly block waiting for concurrent transactions to commit. As committed in this patch, create_index and create_index_spgist have roughly equal runtimes, but that's mostly an artifact of forced synchronization of the CONCURRENTLY tests; when run serially, create_index is much faster. A followup patch will reduce the runtime of create_index_spgist and thereby also create_index.) Discussion: https://postgr.es/m/735.1554935715@sss.pgh.pa.us	7 years ago
Peter Geoghegan	dd299df818	Make heap TID a tiebreaker nbtree index column. ... Make nbtree treat all index tuples as having a heap TID attribute. Index searches can distinguish duplicates by heap TID, since heap TID is always guaranteed to be unique. This general approach has numerous benefits for performance, and is prerequisite to teaching VACUUM to perform "retail index tuple deletion". Naively adding a new attribute to every pivot tuple has unacceptable overhead (it bloats internal pages), so suffix truncation of pivot tuples is added. This will usually truncate away the "extra" heap TID attribute from pivot tuples during a leaf page split, and may also truncate away additional user attributes. This can increase fan-out, especially in a multi-column index. Truncation can only occur at the attribute granularity, which isn't particularly effective, but works well enough for now. A future patch may add support for truncating "within" text attributes by generating truncated key values using new opclass infrastructure. Only new indexes (BTREE_VERSION 4 indexes) will have insertions that treat heap TID as a tiebreaker attribute, or will have pivot tuples undergo suffix truncation during a leaf page split (on-disk compatibility with versions 2 and 3 is preserved). Upgrades to version 4 cannot be performed on-the-fly, unlike upgrades from version 2 to version 3. contrib/amcheck continues to work with version 2 and 3 indexes, while also enforcing stricter invariants when verifying version 4 indexes. These stricter invariants are the same invariants described by "3.1.12 Sequencing" from the Lehman and Yao paper. A later patch will enhance the logic used by nbtree to pick a split point. This patch is likely to negatively impact performance without smarter choices around the precise point to split leaf pages at. Making these two mostly-distinct sets of enhancements into distinct commits seems like it might clarify their design, even though neither commit is particularly useful on its own. The maximum allowed size of new tuples is reduced by an amount equal to the space required to store an extra MAXALIGN()'d TID in a new high key during leaf page splits. The user-facing definition of the "1/3 of a page" restriction is already imprecise, and so does not need to be revised. However, there should be a compatibility note in the v12 release notes. Author: Peter Geoghegan Reviewed-By: Heikki Linnakangas, Alexander Korotkov Discussion: https://postgr.es/m/CAH2-WzkVb0Kom=R+88fDFb=JSxZMFvbHVC6Mn9LJ2n=X=kS-Uw@mail.gmail.com	7 years ago
Tom Lane	74dfe58a59	Allow extensions to generate lossy index conditions. ... For a long time, indxpath.c has had the ability to extract derived (lossy) index conditions from certain operators such as LIKE. For just as long, it's been obvious that we really ought to make that capability available to extensions. This commit finally accomplishes that, by adding another API for planner support functions that lets them create derived index conditions for their functions. As proof of concept, the hardwired "special index operator" code formerly present in indxpath.c is pushed out to planner support functions attached to LIKE and other relevant operators. A weak spot in this design is that an extension needs to know OIDs for the operators, datatypes, and opfamilies involved in the transformation it wants to make. The core-code prototypes use hard-wired OID references but extensions don't have that option for their own operators etc. It's usually possible to look up the required info, but that may be slow and inconvenient. However, improving that situation is a separate task. I want to do some additional refactorization around selfuncs.c, but that also seems like a separate task. Discussion: https://postgr.es/m/15193.1548028093@sss.pgh.pa.us	7 years ago
Teodor Sigaev	857f9c36cd	Skip full index scan during cleanup of B-tree indexes when possible ... Vacuum of index consists from two stages: multiple (zero of more) ambulkdelete calls and one amvacuumcleanup call. When workload on particular table is append-only, then autovacuum isn't intended to touch this table. However, user may run vacuum manually in order to fill visibility map and get benefits of index-only scans. Then ambulkdelete wouldn't be called for indexes of such table (because no heap tuples were deleted), only amvacuumcleanup would be called In this case, amvacuumcleanup would perform full index scan for two objectives: put recyclable pages into free space map and update index statistics. This patch allows btvacuumclanup to skip full index scan when two conditions are satisfied: no pages are going to be put into free space map and index statistics isn't stalled. In order to check first condition, we store oldest btpo_xact in the meta-page. When it's precedes RecentGlobalXmin, then there are some recyclable pages. In order to check second condition we store number of heap tuples observed during previous full index scan by cleanup. If fraction of newly inserted tuples is less than vacuum_cleanup_index_scale_factor, then statistics isn't considered to be stalled. vacuum_cleanup_index_scale_factor can be defined as both reloption and GUC (default). This patch bumps B-tree meta-page version. Upgrade of meta-page is performed "on the fly": during VACUUM meta-page is rewritten with new version. No special handling in pg_upgrade is required. Author: Masahiko Sawada, Alexander Korotkov Review by: Peter Geoghegan, Kyotaro Horiguchi, Alexander Korotkov, Yura Sokolov Discussion: https://www.postgresql.org/message-id/flat/CAD21AoAX+d2oD_nrd9O2YkpzHaFr=uQeGr9s1rKC3O4ENc568g@mail.gmail.com	8 years ago
Heikki Linnakangas	88fc719263	Add test cases for indexam operations not currently covered. ... That includes VACUUM on GIN, GiST and SP-GiST indexes, and B-tree indexes large enough to cause page deletions in B-tree. Plus some other special cases. After this patch, the regression tests generate all different WAL record types. Not all branches within the redo functions are covered, but it's a step forward.	11 years ago
Tom Lane	176961c1f1	Fix breakage of bitmap scan plan creation for special index operators such ... as LIKE. I oversimplified this code when removing support for plan-time determination of index operator lossiness back in April --- I had thought create_bitmap_subplan could stop returning two separate lists of qual conditions, but it still must so that we can treat special operators correctly in create_bitmap_scan_plan. Per report from Rushabh Lathia.	17 years ago
Thomas G. Lockhart	d1e6368816	Clean up header for uniform appearance throughout tests.	26 years ago
Bruce Momjian	0d203b745d	Re-apply Darren's char2-16 removal code.	28 years ago
Bruce Momjian	db21523314	Back out char2-char16 removal. Add later.	28 years ago
Bruce Momjian	57b5966405	The following uuencoded, gzip'd file will ... ... 1. Remove the char2, char4, char8 and char16 types from postgresql 2. Change references of char16 to name in the regression tests. 3. Rename the char16.sql regression test to name.sql. 4. Modify the regression test scripts and outputs to match up. Might require new regression.{SYSTEM} files... Darren King	28 years ago
Marc G. Fournier	f9526f886a	clean up misc.source and create *individual test* files ... trying to move ... away from one big massive confusing file	29 years ago