Hi
> When you say 'without any problem', do you mean to say that the drop
> database is successful? In your tests were those sessions idle? If
> so, I think we should try with busy sessions. Also, if you write any
> script to do these tests, kindly share the same so that others can
> also repeat those tests.
>
I run pgbench on database with -i -S 100 and -c 1000. It is maximum for my
notebook. There was high load - about 50, and still DROP DATABASE FORCE is
working without any problems
> >(under low load (only pg_sleep was called).
> >
>
> I guess this is also possible because immediately after
> TerminateOtherDBBackends, we call CountOtherDBBackends which again
> give 5s to allow active connections to die. I am wondering why not we
> call CountOtherDBBackends from TerminateOtherDBBackends after sending
> the SIGTERM to all the sessions that are connected to the database
> being dropped? Currently, it looks odd that first, we wait for 100ms
> after sending the signal and then separately wait for 5s in another
> function.
>
I checked code, and would not to change calls. Now I think the code is well
readable and has logical sense. But we can decrease sleep in
TerminateOtherDBBackends from 100 ms to 5 ms (just to increase chance to be
all killed processes done, and then waiting in CountOtherDBBackends 100ms
will not be hit.
> Other comments:
> 1.
> diff --git a/src/test/regress/sql/psql.sql b/src/test/regress/sql/psql.sql
> index 26a0bcf718..c8f545be18 100644
> --- a/src/test/regress/sql/psql.sql
> +++ b/src/test/regress/sql/psql.sql
> @@ -1182,3 +1182,11 @@ drop role regress_partitioning_role;
>
> -- \d on toast table (use pg_statistic's toast table, which has a known
> name)
> \d pg_toast.pg_toast_2619
> +
> +--
> +-- DROP DATABASE FORCE test of syntax (should not to raise syntax error)
> +--
> +drop database not_exists (force);
> +drop database not_exists with (force);
> +drop database if exists not_exists (force);
> +drop database if exists not_exists with (force);
>
> I don't think psql.sql is the right place to add such tests.
> Actually, there doesn't appear to be any database specific test file.
> However, if we want to add to any existing file, then maybe
> drop_if_exits.sql could be a better place for these tests as compare
> to psql.sql.
>
moved
> 2.
> + if (nprepared > 0)
> + ereport(ERROR,
> + (errcode(ERRCODE_OBJECT_IN_USE),
> + errmsg_plural("database \"%s\" is used by %d prepared transaction",
> + "database \"%s\" is used by %d prepared transactions",
> + nprepared,
> + get_database_name(databaseId), nprepared)));
>
> I think it is better if we mimic exactly what we have in the failure
> of CountOtherDBBackends.
>
done
Regards
Pavel
> --
> With Regards,
> Amit Kapila.
> EnterpriseDB: http://www.enterprisedb.com
>
diff --git a/doc/src/sgml/ref/drop_database.sgml b/doc/src/sgml/ref/drop_database.sgml
index 3ac06c984a..9b9cabe71c 100644
--- a/doc/src/sgml/ref/drop_database.sgml
+++ b/doc/src/sgml/ref/drop_database.sgml
@@ -21,7 +21,11 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
-DROP DATABASE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
+DROP DATABASE [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [ [ WITH ] ( <replaceable class="parameter">option</replaceable> [, ...] ) ]
+
+<phrase>where <replaceable class="parameter">option</replaceable> can be one of:</phrase>
+
+ FORCE
</synopsis>
</refsynopsisdiv>
@@ -32,9 +36,11 @@ DROP DATABASE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
<command>DROP DATABASE</command> drops a database. It removes the
catalog entries for the database and deletes the directory
containing the data. It can only be executed by the database owner.
- Also, it cannot be executed while you or anyone else are connected
- to the target database. (Connect to <literal>postgres</literal> or any
- other database to issue this command.)
+ Also, it cannot be executed while you are connected to the target database.
+ (Connect to <literal>postgres</literal> or any other database to issue this
+ command.)
+ If anyone else is connected to the target database, this command will fail
+ unless you use the <literal>FORCE</literal> option described below.
</para>
<para>
@@ -64,6 +70,28 @@ DROP DATABASE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
</para>
</listitem>
</varlistentry>
+
+ <varlistentry>
+ <term><literal>FORCE</literal></term>
+ <listitem>
+ <para>
+ Attempt to terminate all existing connections to the target database.
+ It doesn't terminate prepared transactions or active logical replication
+ slot(s).
+ </para>
+ <para>
+ This will fail, if current user has no permissions to terminate other
+ connections. Required permissions are the same as with
+ <literal>pg_terminate_backend</literal>, described
+ in <xref linkend="functions-admin-signal"/>.
+
+ This will fail if we are not able to terminate connections or
+ when there are active prepared transactions or active logical replication
+ slots.
+ </para>
+ </listitem>
+ </varlistentry>
+
</variablelist>
</refsect1>
diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 01d66212e9..8e62359b4d 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -811,7 +811,7 @@ createdb_failure_callback(int code, Datum arg)
* DROP DATABASE
*/
void
-dropdb(const char *dbname, bool missing_ok)
+dropdb(const char *dbname, bool missing_ok, bool force)
{
Oid db_id;
bool db_istemplate;
@@ -896,6 +896,9 @@ dropdb(const char *dbname, bool missing_ok)
nslots_active, nslots_active)));
}
+ if (force)
+ TerminateOtherDBBackends(db_id);
+
/*
* Check for other backends in the target database. (Because we hold the
* database lock, no new ones can start after this.)
@@ -1003,6 +1006,30 @@ dropdb(const char *dbname, bool missing_ok)
ForceSyncCommit();
}
+/*
+ * Process options and call dropdb function.
+ */
+void
+DropDatabase(ParseState *pstate, DropdbStmt *stmt)
+{
+ bool force = false;
+ ListCell *lc;
+
+ foreach(lc, stmt->options)
+ {
+ DefElem *opt = (DefElem *) lfirst(lc);
+
+ if (strcmp(opt->defname, "force") == 0)
+ force = true;
+ else
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("unrecognized DROP DATABASE option \"%s\"", opt->defname),
+ parser_errposition(pstate, opt->location)));
+ }
+
+ dropdb(stmt->dbname, stmt->missing_ok, force);
+}
/*
* Rename database
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 3432bb921d..2f267e4bb6 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -3868,6 +3868,7 @@ _copyDropdbStmt(const DropdbStmt *from)
COPY_STRING_FIELD(dbname);
COPY_SCALAR_FIELD(missing_ok);
+ COPY_NODE_FIELD(options);
return newnode;
}
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 18cb014373..da0e1d139a 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -1676,6 +1676,7 @@ _equalDropdbStmt(const DropdbStmt *a, const DropdbStmt *b)
{
COMPARE_STRING_FIELD(dbname);
COMPARE_SCALAR_FIELD(missing_ok);
+ COMPARE_NODE_FIELD(options);
return true;
}
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 3f67aaf30e..5131099a85 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -310,6 +310,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
%type <defelt> vac_analyze_option_elem
%type <list> vac_analyze_option_list
%type <node> vac_analyze_option_arg
+%type <defelt> drop_option
%type <boolean> opt_or_replace
opt_grant_grant_option opt_grant_admin_option
opt_nowait opt_if_exists opt_with_data
@@ -406,6 +407,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
TriggerTransitions TriggerReferencing
publication_name_list
vacuum_relation_list opt_vacuum_relation_list
+ drop_option_list
%type <list> group_by_list
%type <node> group_by_item empty_grouping_set rollup_clause cube_clause
@@ -10213,7 +10215,7 @@ AlterDatabaseSetStmt:
/*****************************************************************************
*
- * DROP DATABASE [ IF EXISTS ]
+ * DROP DATABASE [ IF EXISTS ] dbname [ [ WITH ] ( options ) ]
*
* This is implicitly CASCADE, no need for drop behavior
*****************************************************************************/
@@ -10223,6 +10225,7 @@ DropdbStmt: DROP DATABASE database_name
DropdbStmt *n = makeNode(DropdbStmt);
n->dbname = $3;
n->missing_ok = false;
+ n->options = NULL;
$$ = (Node *)n;
}
| DROP DATABASE IF_P EXISTS database_name
@@ -10230,10 +10233,48 @@ DropdbStmt: DROP DATABASE database_name
DropdbStmt *n = makeNode(DropdbStmt);
n->dbname = $5;
n->missing_ok = true;
+ n->options = NULL;
$$ = (Node *)n;
}
+ | DROP DATABASE database_name opt_with '(' drop_option_list ')'
+ {
+ DropdbStmt *n = makeNode(DropdbStmt);
+ n->dbname = $3;
+ n->missing_ok = false;
+ n->options = $6;
+ $$ = (Node *)n;
+ }
+ | DROP DATABASE IF_P EXISTS database_name opt_with '(' drop_option_list ')'
+ {
+ DropdbStmt *n = makeNode(DropdbStmt);
+ n->dbname = $5;
+ n->missing_ok = true;
+ n->options = $8;
+ $$ = (Node *)n;
+ }
+ ;
+
+drop_option_list:
+ drop_option
+ {
+ $$ = list_make1((Node *) $1);
+ }
+ | drop_option_list ',' drop_option
+ {
+ $$ = lappend($1, (Node *) $3);
+ }
;
+/*
+ * Currently only the FORCE option is supported, but syntax is designed
+ * to be extensible, and then we use same patterns like on other places.
+ */
+drop_option:
+ FORCE
+ {
+ $$ = makeDefElem("force", NULL, @1);
+ }
+ ;
/*****************************************************************************
*
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 3da53074b1..4a26c005c6 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -52,6 +52,8 @@
#include "access/xact.h"
#include "access/xlog.h"
#include "catalog/catalog.h"
+#include "catalog/pg_authid.h"
+#include "commands/dbcommands.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "storage/proc.h"
@@ -2970,6 +2972,116 @@ CountOtherDBBackends(Oid databaseId, int *nbackends, int *nprepared)
return true; /* timed out, still conflicts */
}
+/*
+ * Terminate other connections to specified database. This routine
+ * is used by DROP DATABASE FORCE to eliminate all others clients from
+ * database to be possible safely drop database.
+ *
+ * It does three steps:
+ *
+ * 1. Collects processes on specified database, and stops
+ * when any process is a prepared transaction.
+ *
+ * 2. Checks if caller has enough rights to terminate collected
+ * processes.
+ *
+ * 3. Send SIGTERM to collected processes and wait 100ms.
+ *
+ */
+void
+TerminateOtherDBBackends(Oid databaseId)
+{
+ ProcArrayStruct *arrayP = procArray;
+ List *pids = NIL;
+ int nprepared = 0;
+ int i;
+
+ LWLockAcquire(ProcArrayLock, LW_SHARED);
+
+ for (i = 0; i < procArray->numProcs; i++)
+ {
+ int pgprocno = arrayP->pgprocnos[i];
+ PGPROC *proc = &allProcs[pgprocno];
+
+ if (proc->databaseId != databaseId)
+ continue;
+ if (proc == MyProc)
+ continue;
+
+ if (proc->pid != 0)
+ pids = lappend_int(pids, proc->pid);
+ else
+ nprepared++;
+ }
+
+ LWLockRelease(ProcArrayLock);
+
+ if (nprepared > 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_OBJECT_IN_USE),
+ errmsg("database \"%s\" is being used by prepared transaction",
+ get_database_name(databaseId)),
+ errdetail_plural("There is %d prepared transaction using the database.",
+ "There are %d prepared transactions using the database.",
+ nprepared,
+ nprepared)));
+
+ if (pids)
+ {
+ ListCell *lc;
+
+ /*
+ * Similar code to pg_terminate_backend, but we check rights first
+ * here, and only when we have all necessary rights we start to
+ * terminate other clients. In this case we should not raise
+ * some warnings - like "PID %d is not a PostgreSQL server process",
+ * because for this purpose - already finished session is not
+ * problem.
+ */
+ foreach (lc, pids)
+ {
+ int pid = lfirst_int(lc);
+ PGPROC *proc = BackendPidGetProc(pid);
+
+ if (proc != NULL)
+ {
+ /* Only allow superusers to signal superuser-owned backends. */
+ if (superuser_arg(proc->roleId) && !superuser())
+ ereport(ERROR,
+ (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+ (errmsg("must be a superuser to terminate superuser process"))));
+
+ /* Users can signal backends they have role membership in. */
+ if (!has_privs_of_role(GetUserId(), proc->roleId) &&
+ !has_privs_of_role(GetUserId(), DEFAULT_ROLE_SIGNAL_BACKENDID))
+ ereport(ERROR,
+ (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+ (errmsg("must be a member of the role whose process is being terminated or member of pg_signal_backend"))));
+ }
+ }
+
+ /* We know so we have all necessary rights now */
+ foreach (lc, pids)
+ {
+ int pid = lfirst_int(lc);
+ PGPROC *proc = BackendPidGetProc(pid);
+
+ if (proc != NULL)
+ {
+ /* If we have setsid(), signal the backend's whole process group */
+#ifdef HAVE_SETSID
+ (void) kill(-pid, SIGTERM);
+#else
+ (void) kill(pid, SIGTERM);
+#endif
+ }
+ }
+
+ /* sleep 5ms */
+ pg_usleep(5 * 1000L);
+ }
+}
+
/*
* ProcArraySetReplicationSlotXmin
*
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index c6faa6619d..960b0df0e1 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -596,13 +596,9 @@ standard_ProcessUtility(PlannedStmt *pstmt,
break;
case T_DropdbStmt:
- {
- DropdbStmt *stmt = (DropdbStmt *) parsetree;
-
- /* no event triggers for global objects */
- PreventInTransactionBlock(isTopLevel, "DROP DATABASE");
- dropdb(stmt->dbname, stmt->missing_ok);
- }
+ /* no event triggers for global objects */
+ PreventInTransactionBlock(isTopLevel, "DROP DATABASE");
+ DropDatabase(pstate, (DropdbStmt *) parsetree);
break;
/* Query-level asynchronous notification */
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index e00dbab5aa..2ac2cff226 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2844,6 +2844,11 @@ psql_completion(const char *text, int start, int end)
COMPLETE_WITH_FUNCTION_ARG(prev2_wd);
else if (Matches("DROP", "FOREIGN"))
COMPLETE_WITH("DATA WRAPPER", "TABLE");
+ else if (Matches("DROP", "DATABASE", MatchAny))
+ COMPLETE_WITH("WITH (");
+ else if (HeadMatches("DROP", "DATABASE") &&
+ (ends_with(prev_wd, '(') || ends_with(prev_wd, ',')))
+ COMPLETE_WITH("FORCE");
/* DROP INDEX */
else if (Matches("DROP", "INDEX"))
diff --git a/src/include/commands/dbcommands.h b/src/include/commands/dbcommands.h
index 154c8157ee..d1e91a2455 100644
--- a/src/include/commands/dbcommands.h
+++ b/src/include/commands/dbcommands.h
@@ -20,7 +20,8 @@
#include "nodes/parsenodes.h"
extern Oid createdb(ParseState *pstate, const CreatedbStmt *stmt);
-extern void dropdb(const char *dbname, bool missing_ok);
+extern void dropdb(const char *dbname, bool missing_ok, bool force);
+extern void DropDatabase(ParseState *pstate, DropdbStmt *stmt);
extern ObjectAddress RenameDatabase(const char *oldname, const char *newname);
extern Oid AlterDatabase(ParseState *pstate, AlterDatabaseStmt *stmt, bool isTopLevel);
extern Oid AlterDatabaseSet(AlterDatabaseSetStmt *stmt);
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index d93a79a554..ff626cbe61 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -3145,6 +3145,7 @@ typedef struct DropdbStmt
NodeTag type;
char *dbname; /* database to drop */
bool missing_ok; /* skip error if db is missing? */
+ List *options; /* currently only FORCE is supported */
} DropdbStmt;
/* ----------------------
diff --git a/src/include/storage/procarray.h b/src/include/storage/procarray.h
index da8b672096..8f67b860e7 100644
--- a/src/include/storage/procarray.h
+++ b/src/include/storage/procarray.h
@@ -113,6 +113,7 @@ extern void CancelDBBackends(Oid databaseid, ProcSignalReason sigmode, bool conf
extern int CountUserBackends(Oid roleid);
extern bool CountOtherDBBackends(Oid databaseId,
int *nbackends, int *nprepared);
+extern void TerminateOtherDBBackends(Oid databaseId);
extern void XidCacheRemoveRunningXids(TransactionId xid,
int nxids, const TransactionId *xids,
diff --git a/src/test/regress/expected/drop_if_exists.out b/src/test/regress/expected/drop_if_exists.out
index 6a17467717..eba0f3f8c7 100644
--- a/src/test/regress/expected/drop_if_exists.out
+++ b/src/test/regress/expected/drop_if_exists.out
@@ -330,3 +330,14 @@ HINT: Specify the argument list to select the routine unambiguously.
-- cleanup
DROP PROCEDURE test_ambiguous_procname(int);
DROP PROCEDURE test_ambiguous_procname(text);
+--
+-- DROP DATABASE FORCE test of syntax (should not to raise syntax error)
+--
+drop database not_exists (force);
+ERROR: database "not_exists" does not exist
+drop database not_exists with (force);
+ERROR: database "not_exists" does not exist
+drop database if exists not_exists (force);
+NOTICE: database "not_exists" does not exist, skipping
+drop database if exists not_exists with (force);
+NOTICE: database "not_exists" does not exist, skipping
diff --git a/src/test/regress/sql/drop_if_exists.sql b/src/test/regress/sql/drop_if_exists.sql
index 8a791b1ef2..03aebb0ee5 100644
--- a/src/test/regress/sql/drop_if_exists.sql
+++ b/src/test/regress/sql/drop_if_exists.sql
@@ -295,3 +295,11 @@ DROP ROUTINE IF EXISTS test_ambiguous_procname;
-- cleanup
DROP PROCEDURE test_ambiguous_procname(int);
DROP PROCEDURE test_ambiguous_procname(text);
+
+--
+-- DROP DATABASE FORCE test of syntax (should not to raise syntax error)
+--
+drop database not_exists (force);
+drop database not_exists with (force);
+drop database if exists not_exists (force);
+drop database if exists not_exists with (force);
