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Robert Haas 7d8ac9814b Charge cpu_tuple_cost * 0.5 for Append and MergeAppend nodes. ... Previously, Append didn't charge anything at all, and MergeAppend charged only cpu_operator_cost, about half the value used here. This change might make MergeAppend plans slightly more likely to be chosen than before, since this commit increases the assumed cost for Append -- with default values -- by 0.005 per tuple but MergeAppend by only 0.0025 per tuple. Since the comparisons required by MergeAppend are costed separately, it's not clear why MergeAppend needs to be otherwise more expensive than Append, so hopefully this is OK. Prior to partition-wise join, it didn't really matter whether or not an Append node had any cost of its own, because every plan had to use the same number of Append or MergeAppend nodes and in the same places. Only the relative cost of Append vs. MergeAppend made a difference. Now, however, it is possible to avoid some of the Append nodes using a partition-wise join, so it's worth making an effort. Pending patches for partition-wise aggregate care too, because an Append of Aggregate nodes will incur the Append overhead fewer times than an Aggregate over an Append. Although in most cases this change will favor the use of partition-wise techniques, it does the opposite when the join cardinality is greater than the sum of the input cardinalities. Since this situation arises in an existing regression test, I [rhaas] adjusted it to keep the overall plan shape approximately the same. Jeevan Chalke, per a suggestion from David Rowley. Reviewed by Ashutosh Bapat. Some changes by me. The larger patch series of which this patch is a part was also reviewed and tested by Antonin Houska, Rajkumar Raghuwanshi, David Rowley, Dilip Kumar, Konstantin Knizhnik, Pascal Legrand, Rafia Sabih, and me. Discussion: http://postgr.es/m/CAKJS1f9UXdk6ZYyqbJnjFO9a9hyHKGW7B=ZRh-rxy9qxfPA5Gw@mail.gmail.com		8 years ago
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backend	Charge cpu_tuple_cost * 0.5 for Append and MergeAppend nodes.	8 years ago
bin	Repair pg_upgrade's failure to preserve relfrozenxid for matviews.	8 years ago
common	Update copyright for 2018	8 years ago
fe_utils	Update copyright for 2018	8 years ago
include	Use platform independent type for TupleTableSlot->tts_off.	8 years ago
interfaces	Refactor client-side SSL certificate checking code	8 years ago
makefiles	Always use -fPIC, not -fpic, when building shared libraries with gcc.	9 years ago
pl	Remove some inappropriate #includes.	8 years ago
port	Add an assertion that we don't pass NULL to snprintf("%s").	8 years ago
template	Force "restrict" not to be used when compiling with xlc.	8 years ago
test	Charge cpu_tuple_cost * 0.5 for Append and MergeAppend nodes.	8 years ago
timezone	Update time zone data files to tzdata release 2018c.	8 years ago
tools	Support parallel btree index builds.	8 years ago
tutorial	Update copyright for 2018	8 years ago
.gitignore	…
DEVELOPERS	…
Makefile	Build src/test/isolation during "make" and "make install".	8 years ago
Makefile.global.in	Convert documentation to DocBook XML	8 years ago
Makefile.shlib	Remove support for bcc and msvc standalone libpq builds	9 years ago
nls-global.mk	…