Re: [HACKERS] IN joining

[Dennis Haney]

Tom Lane wrote: Dennis Haney <[EMAIL PROTECTED]> writes: Joining {b,c} to {a} does not meet any of those four allowed cases. Exactly my point... So why ever bother creating the {b,c} node which is legal by the above definition? We don't, because there is no such join clause. No, but we create the equality via the implied equality mechanism... select * from a, b where a.id = b.id3 and a.id in (select c.id2 from c); rtable is (after in-optimization): resno   refname         relid   inFromCl -----   ---------       -----   -------- 1       a     17143           inFromCl 2       b     17151           inFromCl 3       IN_subquery     [subquery] 4       c     17147           inFromCl in gdb: break joinrels.c:563 commands call bms_is_subset(ininfo->lefthand, rel1->relids) call bms_equal(ininfo->righthand, rel2->relids) call bms_is_subset(ininfo->lefthand, rel2->relids) call bms_equal(ininfo->righthand, rel1->relids) x/t rel1->relids.words x/t rel2->relids.words x/t joinrelids.words p jointype printf "%s\n", pretty_format_node_dump(nodeToString(((RestrictInfo*)((RestrictInfo*)restrictlist)->clause)->clause)) end then we get this join: Breakpoint 4, make_join_rel (root=0x8307bc8, rel1=0x8316920, rel2=0x8316b10, jointype=JOIN_UNIQUE_INNER)     at joinrels.c:563 563             switch (jointype) $92 = 0 '\0' $93 = 1 '\001' $94 = 0 '\0' $95 = 0 '\0' 0x83169ac:      00000000000000000000000000000100 0x8316b9c:      00000000000000000000000000010000 0x832670c:      00000000000000000000000000010100 $96 = JOIN_UNIQUE_INNER    {OPEXPR    :opno 96    :opfuncid 0    :opresulttype 16    :opretset false    :args (       {VAR       :varno 4       :varattno 1       :vartype 23       :vartypmod -1       :varlevelsup 0       :varnoold 4       :varoattno 1       }       {VAR       :varno 2       :varattno 1       :vartype 23       :vartypmod -1       :varlevelsup 0       :varnoold 2       :varoattno 1       }    )    } -- Dennis