Fix cost_incremental_sort for expressions with varno 0
When estimating the number of pre-sorted groups in cost_incremental_sort
we must not pass Vars with varno 0 to estimate_num_groups, which would
cause failues in find_base_rel. This may happen when sorting output of
set operations, thanks to generate_append_tlist.
Unlike recurse_set_operations we can't easily access the original target
list, so if we find any Vars with varno 0, we fall back to the default
estimate DEFAULT_NUM_DISTINCT.
Reported-by: Justin Pryzby
Discussion: https://postgr.es/m/20200411214639.GK2228%40telsasoft.com
Branch
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master
Details
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https://git.postgresql.org/pg/commitdiff/de0dc1a84710f127fdd40f87e783797cc2d69a77
Modified Files
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src/backend/optimizer/path/costsize.c | 54 ++++++++++++++++++++++++--
src/test/regress/expected/incremental_sort.out | 20 ++++++++++
src/test/regress/sql/incremental_sort.sql | 4 ++
3 files changed, 75 insertions(+), 3 deletions(-)
