Tom Lane 5e724125af Fix recently-introduced performance problem in ts_headline(). ... The new hlCover() algorithm that I introduced in commit c9b0c678d turns out to potentially take O(N^2) or worse time on long documents, if there are many occurrences of individual query words but few or no substrings that actually satisfy the query. (One way to hit this behavior is with a "common_word & rare_word" type of query.) This seems unavoidable given the original goal of checking every substring of the document, so we have to back off that idea. Fortunately, it seems unlikely that anyone would really want headlines spanning all of a long document, so we can avoid the worse-than-linear behavior by imposing a maximum length of substring that we'll consider. For now, just hard-wire that maximum length as a multiple of max_words times max_fragments. Perhaps at some point somebody will argue for exposing it as a ts_headline parameter, but I'm hesitant to make such a feature addition in a back-patched bug fix. I also noted that the hlFirstIndex() function I'd added in that commit was unnecessarily stupid: it really only needs to check whether a HeadlineWordEntry's item pointer is null or not. This wouldn't make all that much difference in typical cases with queries having just a few terms, but a cycle shaved is a cycle earned. In addition, add a CHECK_FOR_INTERRUPTS call in TS_execute_recurse. This ensures that hlCover's loop is cancellable if it manages to take a long time, and it may protect some other TS_execute callers as well. Back-patch to 9.6 as the previous commit was. I also chose to add the CHECK_FOR_INTERRUPTS call to 9.5. The old hlCover() algorithm seems to avoid the O(N^2) behavior, at least on the test case I tried, but nonetheless it's not very quick on a long document. Per report from Stephen Frost. Discussion: https://postgr.es/m/20200724160535.GW12375@tamriel.snowman.net		2020-07-31 11:43:12 -04:00
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backend	Fix recently-introduced performance problem in ts_headline().	2020-07-31 11:43:12 -04:00
bin	Switch pg_test_fsync to use binary mode on Windows	2020-07-16 15:53:04 +09:00
common	Replace use of sys_siglist[] with strsignal().	2020-07-15 22:05:12 -04:00
fe_utils	Fix translation of special characters in psql's LaTeX output modes.	2018-11-26 17:32:51 -05:00
include	Avoid direct C access to possibly-null pg_subscription_rel.srsublsn.	2020-07-21 11:40:47 -04:00
interfaces	Stamp 10.13.	2020-05-11 17:12:38 -04:00
makefiles	Select CFLAGS_SL at configure time, not in platform-specific Makefiles.	2019-10-21 12:32:36 -04:00
pl	Translation updates	2020-05-11 13:26:52 +02:00
port	Replace use of sys_siglist[] with strsignal().	2020-07-15 22:05:12 -04:00
template	Select CFLAGS_SL at configure time, not in platform-specific Makefiles.	2019-10-21 12:32:36 -04:00
test	Fix construction of updated-columns bitmap in logical replication.	2020-07-20 13:40:16 -04:00
timezone	Ensure that distributed timezone abbreviation files are plain ASCII.	2020-07-17 11:04:44 -04:00
tools	Avoid need for valgrind suppressions for pg_atomic_init_u64 on some platforms.	2020-06-08 20:03:09 -07:00
tutorial	Phase 2 of pgindent updates.	2017-06-21 15:19:25 -04:00
.gitignore
DEVELOPERS
Makefile	Build src/test/isolation during "make" and "make install".	2017-11-22 20:18:52 -08:00
Makefile.global.in	Select CFLAGS_SL at configure time, not in platform-specific Makefiles.	2019-10-21 12:32:36 -04:00
Makefile.shlib	makefile: use proper linker flags for C++ compiles	2020-03-31 22:26:11 -04:00
nls-global.mk	nls-global.mk: search build dir for source files, too	2016-06-07 18:55:18 -04:00