/*
* CreateJobSchema creates a job schema with the given schema name. Note that
* this function ensures that our pg_ prefixed schema names can be created.
* Further note that the created schema does not become visible to other
* processes until the transaction commits.
*/
static void
CreateJobSchema(StringInfo schemaName)
{
const char *queryString = NULL;
bool oldAllowSystemTableMods = false;
Oid savedUserId = InvalidOid;
int savedSecurityContext = 0;
/* build a CREATE SCHEMA statement */
CreateSchemaStmt *createSchemaStmt = makeNode(CreateSchemaStmt);
createSchemaStmt->schemaname = schemaName->data;
createSchemaStmt->authrole = NULL;
createSchemaStmt->schemaElts = NIL;
/* allow schema names that start with pg_ */
oldAllowSystemTableMods = allowSystemTableMods;
allowSystemTableMods = true;
/* ensure we're allowed to create this schema */
GetUserIdAndSecContext(&savedUserId, &savedSecurityContext);
SetUserIdAndSecContext(CitusExtensionOwner(), SECURITY_LOCAL_USERID_CHANGE);
/* actually create schema, and make it visible */
CreateSchemaCommand(createSchemaStmt, queryString);
CommandCounterIncrement();
/* and reset environment */
SetUserIdAndSecContext(savedUserId, savedSecurityContext);
allowSystemTableMods = oldAllowSystemTableMods;
}
/*
* GetNextPlacementId allocates and returns a unique placementId for
* the placement to be created. This allocation occurs both in shared memory
* and in write ahead logs; writing to logs avoids the risk of having shardId
* collisions.
*
* NB: This can be called by any user; for now we have decided that that's
* ok. We might want to restrict this to users part of a specific role or such
* at some later point.
*/
uint64
GetNextPlacementId(void)
{
text *sequenceName = NULL;
Oid sequenceId = InvalidOid;
Datum sequenceIdDatum = 0;
Oid savedUserId = InvalidOid;
int savedSecurityContext = 0;
Datum placementIdDatum = 0;
uint64 placementId = 0;
/*
* In regression tests, we would like to generate placement IDs consistently
* even if the tests run in parallel. Instead of the sequence, we can use
* the next_placement_id GUC to specify which shard ID the current session
* should generate next. The GUC is automatically increased by 1 every time
* a new placement ID is generated.
*/
if (NextPlacementId > 0)
{
placementId = NextPlacementId;
NextPlacementId += 1;
return placementId;
}
sequenceName = cstring_to_text(PLACEMENTID_SEQUENCE_NAME);
sequenceId = ResolveRelationId(sequenceName);
sequenceIdDatum = ObjectIdGetDatum(sequenceId);
GetUserIdAndSecContext(&savedUserId, &savedSecurityContext);
SetUserIdAndSecContext(CitusExtensionOwner(), SECURITY_LOCAL_USERID_CHANGE);
/* generate new and unique placement id from sequence */
placementIdDatum = DirectFunctionCall1(nextval_oid, sequenceIdDatum);
SetUserIdAndSecContext(savedUserId, savedSecurityContext);
placementId = DatumGetInt64(placementIdDatum);
return placementId;
}
/*
* master_get_new_shardid allocates and returns a unique shardId for the shard
* to be created. This allocation occurs both in shared memory and in write
* ahead logs; writing to logs avoids the risk of having shardId collisions.
*
* Please note that the caller is still responsible for finalizing shard data
* and the shardId with the master node. Further note that this function relies
* on an internal sequence created in initdb to generate unique identifiers.
*
* NB: This can be called by any user; for now we have decided that that's
* ok. We might want to restrict this to users part of a specific role or such
* at some later point.
*/
Datum
master_get_new_shardid(PG_FUNCTION_ARGS)
{
text *sequenceName = cstring_to_text(SHARDID_SEQUENCE_NAME);
Oid sequenceId = ResolveRelationId(sequenceName);
Datum sequenceIdDatum = ObjectIdGetDatum(sequenceId);
Oid savedUserId = InvalidOid;
int savedSecurityContext = 0;
Datum shardIdDatum = 0;
GetUserIdAndSecContext(&savedUserId, &savedSecurityContext);
SetUserIdAndSecContext(CitusExtensionOwner(), SECURITY_LOCAL_USERID_CHANGE);
/* generate new and unique shardId from sequence */
shardIdDatum = DirectFunctionCall1(nextval_oid, sequenceIdDatum);
SetUserIdAndSecContext(savedUserId, savedSecurityContext);
PG_RETURN_DATUM(shardIdDatum);
}
