mirror/postgresql
2
0
Fork 0
mirror of https://git.postgresql.org/git/postgresql.git synced 2025-02-17 19:30:00 +08:00
Code Issues Packages Projects Releases Wiki Activity

pg_upgrade: Retrieve subscription count more efficiently.

Browse Source 
Presently, pg_upgrade obtains the number of subscriptions in the
to-be-upgraded cluster by first querying pg_subscription in every
database for the number of subscriptions in only that database.
Then, in count_old_cluster_subscriptions(), it adds all the values
collected in the first step.  This is expensive, especially when
there are many databases.

Fortunately, there is a better way to retrieve the subscription
count.  Since pg_subscription is a shared catalog, we only need to
connect to a single database and query it once.  This commit
modifies pg_upgrade to use that approach, which also allows us to
trim several lines of code.  In passing, move the call to
get_db_subscription_count(), which has been renamed to
get_subscription_count(), from get_db_rel_and_slot_infos() to the
dedicated >= v17 section in check_and_dump_old_cluster().

We may be able to make similar improvements to
get_old_cluster_logical_slot_infos(), but that is left as a future
exercise.

Reviewed-by: Michael Paquier, Amit Kapila
Discussion: https://postgr.es/m/ZprQJv_TxccN3tkr%40nathan
Backpatch-through: 17
This commit is contained in:
Nathan Bossart 2024-07-24 11:30:33 -05:00
parent 9f21482fe1
commit 364509a2e7
3 changed files with 15 additions and 53 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
src/bin/pg_upgrade/check.c
View File

@ -609,8 +609,10 @@ check_and_dump_old_cluster(bool live_check)
/*
* Subscriptions and their dependencies can be migrated since PG17.
* See comments atop get_db_subscription_count().
* Before that the logical slots are not upgraded, so we will not be
* able to upgrade the logical replication clusters completely.
*/
get_subscription_count(&old_cluster);
check_old_cluster_subscription_state();
}
@ -1797,17 +1799,14 @@ check_new_cluster_subscription_configuration(void)
{
PGresult *res;
PGconn *conn;
int nsubs_on_old;
int max_replication_slots;
/* Subscriptions and their dependencies can be migrated since PG17. */
if (GET_MAJOR_VERSION(old_cluster.major_version) < 1700)
return;
nsubs_on_old = count_old_cluster_subscriptions();
/* Quick return if there are no subscriptions to be migrated. */
if (nsubs_on_old == 0)
if (old_cluster.nsubs == 0)
return;
prep_status("Checking for new cluster configuration for subscriptions");
@ -1821,10 +1820,10 @@ check_new_cluster_subscription_configuration(void)
pg_fatal("could not determine parameter settings on new cluster");
max_replication_slots = atoi(PQgetvalue(res, 0, 0));
if (nsubs_on_old > max_replication_slots)
if (old_cluster.nsubs > max_replication_slots)
pg_fatal("\"max_replication_slots\" (%d) must be greater than or equal to the number of "
"subscriptions (%d) on the old cluster",
max_replication_slots, nsubs_on_old);
max_replication_slots, old_cluster.nsubs);
PQclear(res);
PQfinish(conn);

51
src/bin/pg_upgrade/info.c
View File

@ -28,7 +28,6 @@ static void print_db_infos(DbInfoArr *db_arr);
static void print_rel_infos(RelInfoArr *rel_arr);
static void print_slot_infos(LogicalSlotInfoArr *slot_arr);
static void get_old_cluster_logical_slot_infos(DbInfo *dbinfo, bool live_check);
static void get_db_subscription_count(DbInfo *dbinfo);
/*
@ -293,15 +292,8 @@ get_db_rel_and_slot_infos(ClusterInfo *cluster, bool live_check)
get_rel_infos(cluster, pDbInfo);
/*
* Retrieve the logical replication slots infos and the subscriptions
* count for the old cluster.
*/
if (cluster == &old_cluster)
{
get_old_cluster_logical_slot_infos(pDbInfo, live_check);
get_db_subscription_count(pDbInfo);
}
}
if (cluster == &old_cluster)
@ -748,54 +740,25 @@ count_old_cluster_logical_slots(void)
}
/*
* get_db_subscription_count()
* get_subscription_count()
*
* Gets the number of subscriptions in the database referred to by "dbinfo".
*
* Note: This function will not do anything if the old cluster is pre-PG17.
* This is because before that the logical slots are not upgraded, so we will
* not be able to upgrade the logical replication clusters completely.
* Gets the number of subscriptions in the cluster.
*/
static void
get_db_subscription_count(DbInfo *dbinfo)
void
get_subscription_count(ClusterInfo *cluster)
{
PGconn *conn;
PGresult *res;
/* Subscriptions can be migrated since PG17. */
if (GET_MAJOR_VERSION(old_cluster.major_version) < 1700)
return;
conn = connectToServer(&old_cluster, dbinfo->db_name);
conn = connectToServer(cluster, "template1");
res = executeQueryOrDie(conn, "SELECT count(*) "
"FROM pg_catalog.pg_subscription WHERE subdbid = %u",
dbinfo->db_oid);
dbinfo->nsubs = atoi(PQgetvalue(res, 0, 0));
"FROM pg_catalog.pg_subscription");
cluster->nsubs = atoi(PQgetvalue(res, 0, 0));
PQclear(res);
PQfinish(conn);
}
/*
* count_old_cluster_subscriptions()
*
* Returns the number of subscriptions for all databases.
*
* Note: this function always returns 0 if the old_cluster is PG16 and prior
* because we gather subscriptions only for cluster versions greater than or
* equal to PG17. See get_db_subscription_count().
*/
int
count_old_cluster_subscriptions(void)
{
int nsubs = 0;
for (int dbnum = 0; dbnum < old_cluster.dbarr.ndbs; dbnum++)
nsubs += old_cluster.dbarr.dbs[dbnum].nsubs;
return nsubs;
}
static void
free_db_and_rel_infos(DbInfoArr *db_arr)
{

4
src/bin/pg_upgrade/pg_upgrade.h
View File

@ -197,7 +197,6 @@ typedef struct
* path */
RelInfoArr rel_arr; /* array of all user relinfos */
LogicalSlotInfoArr slot_arr; /* array of all LogicalSlotInfo */
int nsubs; /* number of subscriptions */
} DbInfo;
/*
@ -296,6 +295,7 @@ typedef struct
char major_version_str[64]; /* string PG_VERSION of cluster */
uint32 bin_version; /* version returned from pg_ctl */
const char *tablespace_suffix; /* directory specification */
int nsubs; /* number of subscriptions */
} ClusterInfo;
@ -430,7 +430,7 @@ FileNameMap *gen_db_file_maps(DbInfo *old_db,
const char *new_pgdata);
void get_db_rel_and_slot_infos(ClusterInfo *cluster, bool live_check);
int count_old_cluster_logical_slots(void);
int count_old_cluster_subscriptions(void);
void get_subscription_count(ClusterInfo *cluster);
/* option.c */