1
0
mirror of https://github.com/postgres/postgres.git synced 2025-07-24 14:22:24 +03:00
Files
config
contrib
adminpack
auth_delay
auto_explain
bloom
btree_gin
btree_gist
chkpass
citext
cube
dblink
dict_int
dict_xsyn
earthdistance
file_fdw
fuzzystrmatch
hstore
hstore_plperl
hstore_plpython
intagg
intarray
isn
lo
ltree
ltree_plpython
oid2name
pageinspect
passwordcheck
pg_buffercache
pg_freespacemap
pg_prewarm
pg_standby
pg_stat_statements
pg_trgm
pg_visibility
pgcrypto
pgrowlocks
pgstattuple
postgres_fdw
seg
sepgsql
spi
sslinfo
start-scripts
tablefunc
tcn
test_decoding
expected
specs
concurrent_ddl_dml.spec
delayed_startup.spec
mxact.spec
oldest_xmin.spec
ondisk_startup.spec
snapshot_transfer.spec
sql
.gitignore
Makefile
logical.conf
test_decoding.c
tsearch2
tsm_system_rows
tsm_system_time
unaccent
uuid-ossp
vacuumlo
xml2
Makefile
README
contrib-global.mk
doc
src
.dir-locals.el
.gitattributes
.gitignore
COPYRIGHT
GNUmakefile.in
HISTORY
Makefile
README
README.git
aclocal.m4
configure
configure.in
postgres/contrib/test_decoding/specs
Alvaro Herrera 301b2a1aad Reduce cost of test_decoding's new oldest_xmin test
Change a whole-database VACUUM into doing just pg_attribute, which is
the portion that verifies what we want it to do.  The original
formulation wastes a lot of CPU time, which leads the test to fail when
runtime exceeds isolationtester timeout when it's super-slow, such as
under CLOBBER_CACHE_ALWAYS.  Per buildfarm member friarbird.

It turns out that the previous shape of the test doesn't always detect
the condition it is supposed to detect (on unpatched reorderbuffer
code): the reason is that there is a good chance of encountering a
xl_running_xacts record (logged every 15 seconds) before the checkpoint
-- and because we advance the xmin when we receive that WAL record, and
we *don't* advance the xmin twice consecutively without receiving a
client message in between, that means the xmin is not advanced enough
for the tuple to be pruned from pg_attribute by VACUUM.  So the test
would spuriously pass.

The reason this test deficiency wasn't detected earlier is that HOT
pruning removes the tuple anyway, even if vacuum leaves it in place, so
the test correctly fails (detecting the coding mistake), but for the
wrong reason.

To fix this mess, run the s0_get_changes step twice before vacuum
instead of once: this seems to cause the xmin to be advanced reliably,
wreaking havoc with more certainty.

Author: Arseny Sher
Discussion: https://postgr.es/m/87h8lkuxoa.fsf@ars-thinkpad
2018-07-05 16:54:52 -04:00
..
2014-03-03 16:32:18 -05:00