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Prepare to support non-tables in publications 

This by itself doesn't change any functionality but prepares the way
for having relations other than base tables in publications.

Make arrangements for COPY handling the initial table sync.  For
non-tables we have to use COPY (SELECT ...) instead of directly
copying from the table, but then we have to take care to omit
generated columns from the column list.

Also, remove a hardcoded reference to relkind = 'r' and rely on the
publisher to send only what it can actually publish, which will be
correct even in future cross-version scenarios.

Reviewed-by: Amit Langote <amitlangote09@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CA+HiwqH=Y85vRK3mOdjEkqFK+E=ST=eQiHdpj43L=_eJMOOznQ@mail.gmail.com
This commit is contained in:
Peter Eisentraut 2020-03-19 08:17:50 +01:00
parent 1d253bae57
commit c314c147c0
2 changed files with 28 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
src/backend/replication/logical/tablesync.c
View File

@ -639,8 +639,8 @@ fetch_remote_table_info(char *nspname, char *relname,
WalRcvExecResult *res;
StringInfoData cmd;
TupleTableSlot *slot;
Oid tableRow[2] = {OIDOID, CHAROID};
Oid attrRow[4] = {TEXTOID, OIDOID, INT4OID, BOOLOID};
Oid tableRow[] = {OIDOID, CHAROID, CHAROID};
Oid attrRow[] = {TEXTOID, OIDOID, INT4OID, BOOLOID};
bool isnull;
int natt;
@ -649,16 +649,15 @@ fetch_remote_table_info(char *nspname, char *relname,
/* First fetch Oid and replica identity. */
initStringInfo(&cmd);
appendStringInfo(&cmd, "SELECT c.oid, c.relreplident"
appendStringInfo(&cmd, "SELECT c.oid, c.relreplident, c.relkind"
" FROM pg_catalog.pg_class c"
" INNER JOIN pg_catalog.pg_namespace n"
" ON (c.relnamespace = n.oid)"
" WHERE n.nspname = %s"
" AND c.relname = %s"
" AND c.relkind = 'r'",
" AND c.relname = %s",
quote_literal_cstr(nspname),
quote_literal_cstr(relname));
res = walrcv_exec(wrconn, cmd.data, 2, tableRow);
res = walrcv_exec(wrconn, cmd.data, lengthof(tableRow), tableRow);
if (res->status != WALRCV_OK_TUPLES)
ereport(ERROR,
@ -675,6 +674,8 @@ fetch_remote_table_info(char *nspname, char *relname,
Assert(!isnull);
lrel->replident = DatumGetChar(slot_getattr(slot, 2, &isnull));
Assert(!isnull);
lrel->relkind = DatumGetChar(slot_getattr(slot, 3, &isnull));
Assert(!isnull);
ExecDropSingleTupleTableSlot(slot);
walrcv_clear_result(res);
@ -696,7 +697,7 @@ fetch_remote_table_info(char *nspname, char *relname,
lrel->remoteid,
(walrcv_server_version(wrconn) >= 120000 ? "AND a.attgenerated = ''" : ""),
lrel->remoteid);
res = walrcv_exec(wrconn, cmd.data, 4, attrRow);
res = walrcv_exec(wrconn, cmd.data, lengthof(attrRow), attrRow);
if (res->status != WALRCV_OK_TUPLES)
ereport(ERROR,
@ -765,8 +766,25 @@ copy_table(Relation rel)
/* Start copy on the publisher. */
initStringInfo(&cmd);
appendStringInfo(&cmd, "COPY %s TO STDOUT",
quote_qualified_identifier(lrel.nspname, lrel.relname));
if (lrel.relkind == RELKIND_RELATION)
appendStringInfo(&cmd, "COPY %s TO STDOUT",
quote_qualified_identifier(lrel.nspname, lrel.relname));
else
{
/*
* For non-tables, we need to do COPY (SELECT ...), but we can't just
* do SELECT * because we need to not copy generated columns.
*/
appendStringInfo(&cmd, "COPY (SELECT ");
for (int i = 0; i < lrel.natts; i++)
{
appendStringInfoString(&cmd, quote_identifier(lrel.attnames[i]));
if (i < lrel.natts - 1)
appendStringInfoString(&cmd, ", ");
}
appendStringInfo(&cmd, " FROM %s) TO STDOUT",
quote_qualified_identifier(lrel.nspname, lrel.relname));
}
res = walrcv_exec(wrconn, cmd.data, 0, NULL);
pfree(cmd.data);
if (res->status != WALRCV_OK_COPY_OUT)

1
src/include/replication/logicalproto.h
View File

@ -49,6 +49,7 @@ typedef struct LogicalRepRelation
char **attnames; /* column names */
Oid *atttyps; /* column types */
char replident; /* replica identity */
char relkind; /* remote relation kind */
Bitmapset *attkeys; /* Bitmap of key columns */
} LogicalRepRelation;