Add infrastructure to support EphemeralNamedRelation references.

A QueryEnvironment concept is added, which allows new types of
objects to be passed into queries from parsing on through
execution.  At this point, the only thing implemented is a
collection of EphemeralNamedRelation objects -- relations which
can be referenced by name in queries, but do not exist in the
catalogs.  The only type of ENR implemented is NamedTuplestore, but
provision is made to add more types fairly easily.

An ENR can carry its own TupleDesc or reference a relation in the
catalogs by relid.

Although these features can be used without SPI, convenience
functions are added to SPI so that ENRs can easily be used by code
run through SPI.

The initial use of all this is going to be transition tables in
AFTER triggers, but that will be added to each PL as a separate
commit.

An incidental effect of this patch is to produce a more informative
error message if an attempt is made to modify the contents of a CTE
from a referencing DML statement.  No tests previously covered that
possibility, so one is added.

Kevin Grittner and Thomas Munro
Reviewed by Heikki Linnakangas, David Fetter, and Thomas Munro
with valuable comments and suggestions from many others

1 files changed, 7 insertions, 0 deletions

diff --git a/src/include/executor/spi.h b/src/include/executor/spi.h
index a18ae63245..e2e8bb9553 100644
--- a/src/include/executor/spi.h
+++ b/src/include/executor/spi.h
@@ -43,6 +43,8 @@ typedef struct _SPI_plan *SPIPlanPtr;
 #define SPI_ERROR_NOATTRIBUTE	(-9)
 #define SPI_ERROR_NOOUTFUNC		(-10)
 #define SPI_ERROR_TYPUNKNOWN	(-11)
+#define SPI_ERROR_REL_DUPLICATE	(-12)
+#define SPI_ERROR_REL_NOT_FOUND	(-13)
 
 #define SPI_OK_CONNECT			1
 #define SPI_OK_FINISH			2
@@ -58,6 +60,8 @@ typedef struct _SPI_plan *SPIPlanPtr;
 #define SPI_OK_DELETE_RETURNING 12
 #define SPI_OK_UPDATE_RETURNING 13
 #define SPI_OK_REWRITTEN		14
+#define SPI_OK_REL_REGISTER		15
+#define SPI_OK_REL_UNREGISTER	16
 
 /* These used to be functions, now just no-ops for backwards compatibility */
 #define SPI_push()	((void) 0)
@@ -146,6 +150,9 @@ extern void SPI_scroll_cursor_fetch(Portal, FetchDirection direction, long count
 extern void SPI_scroll_cursor_move(Portal, FetchDirection direction, long count);
 extern void SPI_cursor_close(Portal portal);
 
+extern int SPI_register_relation(EphemeralNamedRelation enr);
+extern int SPI_unregister_relation(const char *name);
+
 extern void AtEOXact_SPI(bool isCommit);
 extern void AtEOSubXact_SPI(bool isCommit, SubTransactionId mySubid);