Hi! On 25.1.2014 22:21, Heikki Linnakangas wrote: > Attached is a new version of the patch set, with those bugs fixed.
I've done a bunch of tests with all the 4 patches applied, and it seems to work now. I've done tests with various conditions (AND/OR, number of words, number of conditions) and I so far I did not get any crashes, infinite loops or anything like that. I've also compared the results to 9.3 - by dumping the database and running the same set of queries on both machines, and indeed I got 100% match. I also did some performance tests, and that's when I started to worry. For example, I generated and ran 1000 queries that look like this: SELECT id FROM messages WHERE body_tsvector @@ to_tsquery('english','(header & 53 & 32 & useful & dropped)') ORDER BY ts_rank(body_tsvector, to_tsquery('english','(header & 53 & 32 & useful & dropped)')) DESC; i.e. in this case the query always was 5 words connected by AND. This query is a pretty common pattern for fulltext search - sort by a list of words and give me the best ranked results. On 9.3, the script was running for ~23 seconds, on patched HEAD it was ~40. It's perfectly reproducible, I've repeated the test several times with exactly the same results. The test is CPU bound, there's no I/O activity at all. I got the same results with more queries (~100k). Attached is a simple chart with x-axis used for durations measured on 9.3.2, y-axis used for durations measured on patched HEAD. It's obvious a vast majority of queries is up to 2x slower - that's pretty obvious from the chart. Only about 50 queries are faster on HEAD, and >700 queries are more than 50% slower on HEAD (i.e. if the query took 100ms on 9.3, it takes >150ms on HEAD). Typically, the EXPLAIN ANALYZE looks something like this (on 9.3): http://explain.depesz.com/s/5tv and on HEAD (same query): http://explain.depesz.com/s/1lI Clearly the main difference is in the "Bitmap Index Scan" which takes 60ms on 9.3 and 120ms on HEAD. On 9.3 the "perf top" looks like this: 34.79% postgres [.] gingetbitmap 28.96% postgres [.] ginCompareItemPointers 9.36% postgres [.] TS_execute 5.36% postgres [.] check_stack_depth 3.57% postgres [.] FunctionCall8Coll while on 9.4 it looks like this: 28.20% postgres [.] gingetbitmap 21.17% postgres [.] TS_execute 8.08% postgres [.] check_stack_depth 7.11% postgres [.] FunctionCall8Coll 4.34% postgres [.] shimTriConsistentFn Not sure how to interpret that, though. For example where did the ginCompareItemPointers go? I suspect it's thanks to inlining, and that it might be related to the performance decrease. Or maybe not. I've repeated the test several times, checked all I could think of, but I've found nothing so far. The flags were exactly the same in both cases (just --enable-debug and nothing else). regards Tomas
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