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Improve ExecModifyTable comments.

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Some of these comments wrongly implied that only an AFTER ROW trigger
will cause a 'wholerow' attribute to be present for a foreign table,
but a BEFORE ROW trigger can have the same effect.  Others implied
that it would always be present for a foreign table, but that's not
true either.

Etsuro Fujita and Robert Haas

Discussion: http://postgr.es/m/10026bc7-1403-ef85-9e43-c6100c1cc0e3@lab.ntt.co.jp
This commit is contained in:
Robert Haas 2017-08-03 12:47:00 -04:00
parent 610e8ebb0f
commit 12a34f59bf
1 changed files with 7 additions and 4 deletions
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11
src/backend/executor/nodeModifyTable.c
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@ -1696,7 +1696,7 @@ ExecModifyTable(PlanState *pstate)
* the old relation tuple.
*
* Foreign table updates have a wholerow attribute when the
* relation has an AFTER ROW trigger. Note that the wholerow
* relation has a row-level trigger. Note that the wholerow
* attribute does not carry system columns. Foreign table
* triggers miss seeing those, except that we know enough here
* to set t_tableOid. Quite separately from this, the FDW may
@ -2182,8 +2182,11 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
/*
* Initialize the junk filter(s) if needed. INSERT queries need a filter
* if there are any junk attrs in the tlist. UPDATE and DELETE always
* need a filter, since there's always a junk 'ctid' or 'wholerow'
* attribute present --- no need to look first.
* need a filter, since there's always at least one junk attribute present
* --- no need to look first. Typically, this will be a 'ctid' or
* 'wholerow' attribute, but in the case of a foreign data wrapper it
* might be a set of junk attributes sufficient to identify the remote
* row.
*
* If there are multiple result relations, each one needs its own junk
* filter. Note multiple rels are only possible for UPDATE/DELETE, so we
@ -2251,7 +2254,7 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
else if (relkind == RELKIND_FOREIGN_TABLE)
{
/*
* When there is an AFTER trigger, there should be a
* When there is a row-level trigger, there should be a
* wholerow attribute.
*/
j->jf_junkAttNo = ExecFindJunkAttribute(j, "wholerow");