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Follow-on cleanup for the transition table patch.

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Commit 59702716 added transition table support to PL/pgsql so that
SQL queries in trigger functions could access those transient
tables.  In order to provide the same level of support for PL/perl,
PL/python and PL/tcl, refactor the relevant code into a new
function SPI_register_trigger_data.  Call the new function in the
trigger handler of all four PLs, and document it as a public SPI
function so that authors of out-of-tree PLs can do the same.

Also get rid of a second QueryEnvironment object that was
maintained by PL/pgsql.  That was previously used to deal with
cursors, but the same approach wasn't appropriate for PLs that are
less tangled up with core code.  Instead, have SPI_cursor_open
install the connection's current QueryEnvironment, as already
happens for SPI_execute_plan.

While in the docs, remove the note that transition tables were only
supported in C and PL/pgSQL triggers, and correct some ommissions.

Thomas Munro with some work by Kevin Grittner (mostly docs)
This commit is contained in:
Kevin Grittner
2017-04-04 18:36:39 -05:00
parent 9a3215026b
commit 5ebeb579b9
16 changed files with 398 additions and 63 deletions
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52
src/backend/executor/spi.c
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@ -1257,6 +1257,9 @@ SPI_cursor_open_internal(const char *name, SPIPlanPtr plan,
errdetail("Scrollable cursors must be READ ONLY.")));
}
/* Make current query environment available to portal at execution time. */
portal->queryEnv = _SPI_current->queryEnv;
/*
* If told to be read-only, or in parallel mode, verify that this query is
* in fact read-only. This can't be done earlier because we need to look
@ -2716,3 +2719,52 @@ SPI_unregister_relation(const char *name)
return res;
}
/*
* Register the transient relations from 'tdata' using this SPI connection.
* This should be called by PL implementations' trigger handlers after
* connecting, in order to make transition tables visible to any queries run
* in this connection.
*/
int
SPI_register_trigger_data(TriggerData *tdata)
{
if (tdata == NULL)
return SPI_ERROR_ARGUMENT;
if (tdata->tg_newtable)
{
EphemeralNamedRelation enr =
palloc(sizeof(EphemeralNamedRelationData));
int rc;
enr->md.name = tdata->tg_trigger->tgnewtable;
enr->md.reliddesc = tdata->tg_relation->rd_id;
enr->md.tupdesc = NULL;
enr->md.enrtype = ENR_NAMED_TUPLESTORE;
enr->md.enrtuples = tuplestore_tuple_count(tdata->tg_newtable);
enr->reldata = tdata->tg_newtable;
rc = SPI_register_relation(enr);
if (rc != SPI_OK_REL_REGISTER)
return rc;
}
if (tdata->tg_oldtable)
{
EphemeralNamedRelation enr =
palloc(sizeof(EphemeralNamedRelationData));
int rc;
enr->md.name = tdata->tg_trigger->tgoldtable;
enr->md.reliddesc = tdata->tg_relation->rd_id;
enr->md.tupdesc = NULL;
enr->md.enrtype = ENR_NAMED_TUPLESTORE;
enr->md.enrtuples = tuplestore_tuple_count(tdata->tg_oldtable);
enr->reldata = tdata->tg_oldtable;
rc = SPI_register_relation(enr);
if (rc != SPI_OK_REL_REGISTER)
return rc;
}
return SPI_OK_TD_REGISTER;
}