Merge branch 'collectd-4.5'
[collectd.git] / src / postgresql.c
index 40f8ec5..a5bacf4 100644 (file)
 #define log_warn(...) WARNING ("postgresql: " __VA_ARGS__)
 #define log_info(...) INFO ("postgresql: " __VA_ARGS__)
 
+#ifndef C_PSQL_DEFAULT_CONF
+# define C_PSQL_DEFAULT_CONF PKGDATADIR "/postgresql_default.conf"
+#endif
+
 /* Appends the (parameter, value) pair to the string
  * pointed to by 'buf' suitable to be used as argument
  * for PQconnectdb(). If value equals NULL, the pair
        C_PSQL_IS_UNIX_DOMAIN_SOCKET (host) ? "/.s.PGSQL." : ":", \
        port
 
+typedef enum {
+       C_PSQL_PARAM_HOST = 1,
+       C_PSQL_PARAM_DB,
+       C_PSQL_PARAM_USER,
+} c_psql_param_t;
+
+typedef struct {
+       char *type;
+       char *type_instance;
+       int   ds_type;
+} c_psql_col_t;
+
+typedef struct {
+       char *name;
+       char *query;
+
+       c_psql_param_t *params;
+       int             params_num;
+
+       c_psql_col_t *cols;
+       int           cols_num;
+
+       int min_pg_version;
+       int max_pg_version;
+} c_psql_query_t;
+
 typedef struct {
        PGconn      *conn;
        c_complain_t conn_complaint;
 
+       int proto_version;
+
+       int max_params_num;
+
        /* user configuration */
+       c_psql_query_t **queries;
+       int              queries_num;
+
        char *host;
        char *port;
        char *database;
@@ -90,9 +127,141 @@ typedef struct {
        char *service;
 } c_psql_database_t;
 
+static char *def_queries[] = {
+       "backends",
+       "transactions",
+       "queries",
+       "query_plans",
+       "table_states",
+       "disk_io",
+       "disk_usage"
+};
+static int def_queries_num = STATIC_ARRAY_SIZE (def_queries);
+
+static c_psql_query_t *queries          = NULL;
+static int             queries_num      = 0;
+
 static c_psql_database_t *databases     = NULL;
 static int                databases_num = 0;
 
+static c_psql_query_t *c_psql_query_new (const char *name)
+{
+       c_psql_query_t *query;
+
+       ++queries_num;
+       if (NULL == (queries = (c_psql_query_t *)realloc (queries,
+                               queries_num * sizeof (*queries)))) {
+               log_err ("Out of memory.");
+               exit (5);
+       }
+       query = queries + queries_num - 1;
+
+       query->name  = sstrdup (name);
+       query->query = NULL;
+
+       query->params     = NULL;
+       query->params_num = 0;
+
+       query->cols     = NULL;
+       query->cols_num = 0;
+
+       query->min_pg_version = 0;
+       query->max_pg_version = INT_MAX;
+       return query;
+} /* c_psql_query_new */
+
+static void c_psql_query_delete (c_psql_query_t *query)
+{
+       int i;
+
+       sfree (query->name);
+       sfree (query->query);
+
+       sfree (query->params);
+       query->params_num = 0;
+
+       for (i = 0; i < query->cols_num; ++i) {
+               sfree (query->cols[i].type);
+               sfree (query->cols[i].type_instance);
+       }
+       sfree (query->cols);
+       query->cols_num = 0;
+       return;
+} /* c_psql_query_delete */
+
+static c_psql_query_t *c_psql_query_get (const char *name, int server_version)
+{
+       int i;
+
+       for (i = 0; i < queries_num; ++i)
+               if (0 == strcasecmp (name, queries[i].name)
+                               && ((-1 == server_version)
+                                       || ((queries[i].min_pg_version <= server_version)
+                                               && (server_version <= queries[i].max_pg_version))))
+                       return queries + i;
+       return NULL;
+} /* c_psql_query_get */
+
+static c_psql_database_t *c_psql_database_new (const char *name)
+{
+       c_psql_database_t *db;
+
+       ++databases_num;
+       if (NULL == (databases = (c_psql_database_t *)realloc (databases,
+                               databases_num * sizeof (*databases)))) {
+               log_err ("Out of memory.");
+               exit (5);
+       }
+
+       db = databases + (databases_num - 1);
+
+       db->conn = NULL;
+
+       C_COMPLAIN_INIT (&db->conn_complaint);
+
+       db->proto_version = 0;
+
+       db->max_params_num = 0;
+
+       db->queries     = NULL;
+       db->queries_num = 0;
+
+       db->database   = sstrdup (name);
+       db->host       = NULL;
+       db->port       = NULL;
+       db->user       = NULL;
+       db->password   = NULL;
+
+       db->sslmode    = NULL;
+
+       db->krbsrvname = NULL;
+
+       db->service    = NULL;
+       return db;
+} /* c_psql_database_new */
+
+static void c_psql_database_delete (c_psql_database_t *db)
+{
+       PQfinish (db->conn);
+       db->conn = NULL;
+
+       sfree (db->queries);
+       db->queries_num = 0;
+
+       sfree (db->database);
+       sfree (db->host);
+       sfree (db->port);
+       sfree (db->user);
+       sfree (db->password);
+
+       sfree (db->sslmode);
+
+       sfree (db->krbsrvname);
+
+       sfree (db->service);
+       return;
+} /* c_psql_database_delete */
+
 static void submit (const c_psql_database_t *db,
                const char *type, const char *type_instance,
                value_t *values, size_t values_len)
@@ -167,6 +336,11 @@ static int c_psql_check_connection (c_psql_database_t *db)
                                        db->database, PQerrorMessage (db->conn));
                        return -1;
                }
+
+               db->proto_version = PQprotocolVersion (db->conn);
+               if (3 > db->proto_version)
+                       log_warn ("Protocol version %d does not support parameters.",
+                                       db->proto_version);
        }
 
        c_release (LOG_INFO, &db->conn_complaint,
@@ -174,141 +348,106 @@ static int c_psql_check_connection (c_psql_database_t *db)
        return 0;
 } /* c_psql_check_connection */
 
-static int c_psql_stat_database (c_psql_database_t *db)
+static PGresult *c_psql_exec_query_params (c_psql_database_t *db,
+               c_psql_query_t *query)
 {
-       const char *const query =
-               "SELECT numbackends, xact_commit, xact_rollback "
-                       "FROM pg_stat_database "
-                       "WHERE datname = $1;";
-
-       PGresult *res;
-
-       int n;
-
-       res = PQexecParams (db->conn, query, /* number of parameters */ 1,
-                       NULL, (const char *const *)&db->database, NULL, NULL,
-                       /* return text data */ 0);
-
-       if (PGRES_TUPLES_OK != PQresultStatus (res)) {
-               log_err ("Failed to execute SQL query: %s",
-                               PQerrorMessage (db->conn));
-               log_info ("SQL query was: %s", query);
-               PQclear (res);
-               return -1;
-       }
-
-       n = PQntuples (res);
-       if (1 < n) {
-               log_warn ("pg_stat_database has more than one entry "
-                               "for database %s - ignoring additional results.",
-                               db->database);
-       }
-       else if (1 > n) {
-               log_err ("pg_stat_database has no entry for database %s",
-                               db->database);
-               PQclear (res);
-               return -1;
+       char *params[db->max_params_num];
+       int   i;
+
+       assert (db->max_params_num >= query->params_num);
+
+       for (i = 0; i < query->params_num; ++i) {
+               switch (query->params[i]) {
+                       case C_PSQL_PARAM_HOST:
+                               params[i] = C_PSQL_IS_UNIX_DOMAIN_SOCKET (db->host)
+                                       ? "localhost" : db->host;
+                               break;
+                       case C_PSQL_PARAM_DB:
+                               params[i] = db->database;
+                               break;
+                       case C_PSQL_PARAM_USER:
+                               params[i] = db->user;
+                               break;
+                       default:
+                               assert (0);
+               }
        }
 
-       submit_gauge (db, "pg_numbackends", NULL,  PQgetvalue (res, 0, 0));
+       return PQexecParams (db->conn, query->query, query->params_num, NULL,
+                       (const char *const *)((0 == query->params_num) ? NULL : params),
+                       NULL, NULL, /* return text data */ 0);
+} /* c_psql_exec_query_params */
 
-       submit_counter (db, "pg_xact", "commit",   PQgetvalue (res, 0, 1));
-       submit_counter (db, "pg_xact", "rollback", PQgetvalue (res, 0, 2));
-
-       PQclear (res);
-       return 0;
-} /* c_psql_stat_database */
+static PGresult *c_psql_exec_query_noparams (c_psql_database_t *db,
+               c_psql_query_t *query)
+{
+       return PQexec (db->conn, query->query);
+} /* c_psql_exec_query_noparams */
 
-static int c_psql_stat_user_tables (c_psql_database_t *db)
+static int c_psql_exec_query (c_psql_database_t *db, int idx)
 {
-       const char *const query =
-               "SELECT sum(seq_scan), sum(seq_tup_read), "
-                               "sum(idx_scan), sum(idx_tup_fetch), "
-                               "sum(n_tup_ins), sum(n_tup_upd), sum(n_tup_del), "
-                               "sum(n_tup_hot_upd), sum(n_live_tup), sum(n_dead_tup) "
-                       "FROM pg_stat_user_tables;";
+       c_psql_query_t *query;
+       PGresult       *res;
+
+       int rows, cols;
+       int i;
 
-       PGresult *res;
+       if (idx >= db->queries_num)
+               return -1;
 
-       int n;
+       query = db->queries[idx];
 
-       res = PQexec (db->conn, query);
+       if (3 <= db->proto_version)
+               res = c_psql_exec_query_params (db, query);
+       else if (0 == query->params_num)
+               res = c_psql_exec_query_noparams (db, query);
+       else {
+               log_err ("Connection to database \"%s\" does not support parameters "
+                               "(protocol version %d) - cannot execute query \"%s\".",
+                               db->database, db->proto_version, query->name);
+               return -1;
+       }
 
        if (PGRES_TUPLES_OK != PQresultStatus (res)) {
                log_err ("Failed to execute SQL query: %s",
                                PQerrorMessage (db->conn));
-               log_info ("SQL query was: %s", query);
+               log_info ("SQL query was: %s", query->query);
                PQclear (res);
                return -1;
        }
 
-       n = PQntuples (res);
-       assert (1 >= n);
-
-       if (1 > n) /* no user tables */
+       rows = PQntuples (res);
+       if (1 > rows) {
+               PQclear (res);
                return 0;
+       }
 
-       submit_counter (db, "pg_scan", "seq",           PQgetvalue (res, 0, 0));
-       submit_counter (db, "pg_scan", "seq_tup_read",  PQgetvalue (res, 0, 1));
-       submit_counter (db, "pg_scan", "idx",           PQgetvalue (res, 0, 2));
-       submit_counter (db, "pg_scan", "idx_tup_fetch", PQgetvalue (res, 0, 3));
-
-       submit_counter (db, "pg_n_tup_c", "ins",        PQgetvalue (res, 0, 4));
-       submit_counter (db, "pg_n_tup_c", "upd",        PQgetvalue (res, 0, 5));
-       submit_counter (db, "pg_n_tup_c", "del",        PQgetvalue (res, 0, 6));
-       submit_counter (db, "pg_n_tup_c", "hot_upd",    PQgetvalue (res, 0, 7));
-
-       submit_gauge (db, "pg_n_tup_g", "live",         PQgetvalue (res, 0, 8));
-       submit_gauge (db, "pg_n_tup_g", "dead",         PQgetvalue (res, 0, 9));
-
-       PQclear (res);
-       return 0;
-} /* c_psql_stat_user_tables */
-
-static int c_psql_statio_user_tables (c_psql_database_t *db)
-{
-       const char *const query =
-               "SELECT sum(heap_blks_read), sum(heap_blks_hit), "
-                               "sum(idx_blks_read), sum(idx_blks_hit), "
-                               "sum(toast_blks_read), sum(toast_blks_hit), "
-                               "sum(tidx_blks_read), sum(tidx_blks_hit) "
-                       "FROM pg_statio_user_tables;";
-
-       PGresult *res;
-
-       int n;
-
-       res = PQexec (db->conn, query);
-
-       if (PGRES_TUPLES_OK != PQresultStatus (res)) {
-               log_err ("Failed to execute SQL query: %s",
-                               PQerrorMessage (db->conn));
-               log_info ("SQL query was: %s", query);
+       cols = PQnfields (res);
+       if (query->cols_num != cols) {
+               log_err ("SQL query returned wrong number of fields "
+                               "(expected: %i, got: %i)", query->cols_num, cols);
+               log_info ("SQL query was: %s", query->query);
                PQclear (res);
                return -1;
        }
 
-       n = PQntuples (res);
-       assert (1 >= n);
-
-       if (1 > n) /* no user tables */
-               return 0;
-
-       submit_counter (db, "pg_blks", "heap_read",  PQgetvalue (res, 0, 0));
-       submit_counter (db, "pg_blks", "heap_hit",   PQgetvalue (res, 0, 1));
-
-       submit_counter (db, "pg_blks", "idx_read",   PQgetvalue (res, 0, 2));
-       submit_counter (db, "pg_blks", "idx_hit",    PQgetvalue (res, 0, 3));
+       for (i = 0; i < rows; ++i) {
+               int j;
 
-       submit_counter (db, "pg_blks", "toast_read", PQgetvalue (res, 0, 4));
-       submit_counter (db, "pg_blks", "toast_hit",  PQgetvalue (res, 0, 5));
+               for (j = 0; j < cols; ++j) {
+                       c_psql_col_t col = query->cols[j];
 
-       submit_counter (db, "pg_blks", "tidx_read",  PQgetvalue (res, 0, 6));
-       submit_counter (db, "pg_blks", "tidx_hit",   PQgetvalue (res, 0, 7));
+                       char *value = PQgetvalue (res, i, j);
 
+                       if (col.ds_type == DS_TYPE_COUNTER)
+                               submit_counter (db, col.type, col.type_instance, value);
+                       else if (col.ds_type == DS_TYPE_GAUGE)
+                               submit_gauge (db, col.type, col.type_instance, value);
+               }
+       }
        PQclear (res);
        return 0;
-} /* c_psql_statio_user_tables */
+} /* c_psql_exec_query */
 
 static int c_psql_read (void)
 {
@@ -318,14 +457,15 @@ static int c_psql_read (void)
        for (i = 0; i < databases_num; ++i) {
                c_psql_database_t *db = databases + i;
 
+               int j;
+
                assert (NULL != db->database);
 
                if (0 != c_psql_check_connection (db))
                        continue;
 
-               c_psql_stat_database (db);
-               c_psql_stat_user_tables (db);
-               c_psql_statio_user_tables (db);
+               for (j = 0; j < db->queries_num; ++j)
+                       c_psql_exec_query (db, j);
 
                ++success;
        }
@@ -347,24 +487,19 @@ static int c_psql_shutdown (void)
 
        for (i = 0; i < databases_num; ++i) {
                c_psql_database_t *db = databases + i;
-
-               PQfinish (db->conn);
-
-               sfree (db->database);
-               sfree (db->host);
-               sfree (db->port);
-               sfree (db->user);
-               sfree (db->password);
-
-               sfree (db->sslmode);
-
-               sfree (db->krbsrvname);
-
-               sfree (db->service);
+               c_psql_database_delete (db);
        }
 
        sfree (databases);
        databases_num = 0;
+
+       for (i = 0; i < queries_num; ++i) {
+               c_psql_query_t *query = queries + i;
+               c_psql_query_delete (query);
+       }
+
+       sfree (queries);
+       queries_num = 0;
        return 0;
 } /* c_psql_shutdown */
 
@@ -375,6 +510,33 @@ static int c_psql_init (void)
        if ((NULL == databases) || (0 == databases_num))
                return 0;
 
+       for (i = 0; i < queries_num; ++i) {
+               c_psql_query_t *query = queries + i;
+               int j;
+
+               for (j = 0; j < query->cols_num; ++j) {
+                       c_psql_col_t     *col = query->cols + j;
+                       const data_set_t *ds;
+
+                       ds = plugin_get_ds (col->type);
+                       if (NULL == ds) {
+                               log_err ("Column: Unknown type \"%s\".", col->type);
+                               c_psql_shutdown ();
+                               return -1;
+                       }
+
+                       if (1 != ds->ds_num) {
+                               log_err ("Column: Invalid type \"%s\" - types defining "
+                                               "one data source are supported only (got: %i).",
+                                               col->type, ds->ds_num);
+                               c_psql_shutdown ();
+                               return -1;
+                       }
+
+                       col->ds_type = ds->ds[0].type;
+               }
+       }
+
        for (i = 0; i < databases_num; ++i) {
                c_psql_database_t *db = databases + i;
 
@@ -386,6 +548,14 @@ static int c_psql_init (void)
                char *server_host;
                int   server_version;
 
+               int j;
+
+               /* this will happen during reinitialization */
+               if (NULL != db->conn) {
+                       c_psql_check_connection (db);
+                       continue;
+               }
+
                status = ssnprintf (buf, buf_len, "dbname = '%s'", db->database);
                if (0 < status) {
                        buf     += status;
@@ -404,15 +574,48 @@ static int c_psql_init (void)
                if (0 != c_psql_check_connection (db))
                        continue;
 
+               db->proto_version = PQprotocolVersion (db->conn);
+
                server_host    = PQhost (db->conn);
                server_version = PQserverVersion (db->conn);
                log_info ("Sucessfully connected to database %s (user %s) "
                                "at server %s%s%s (server version: %d.%d.%d, "
                                "protocol version: %d, pid: %d)",
                                PQdb (db->conn), PQuser (db->conn),
-                               C_PSQL_SOCKET3(server_host, PQport (db->conn)),
+                               C_PSQL_SOCKET3 (server_host, PQport (db->conn)),
                                C_PSQL_SERVER_VERSION3 (server_version),
-                               PQprotocolVersion (db->conn), PQbackendPID (db->conn));
+                               db->proto_version, PQbackendPID (db->conn));
+
+               if (3 > db->proto_version)
+                       log_warn ("Protocol version %d does not support parameters.",
+                                       db->proto_version);
+
+               /* Now that we know the PostgreSQL server version, we can get the
+                * right version of each query definition. */
+               for (j = 0; j < db->queries_num; ++j) {
+                       c_psql_query_t *tmp;
+
+                       tmp = c_psql_query_get (db->queries[j]->name, server_version);
+
+                       if (tmp == db->queries[j])
+                               continue;
+
+                       if (NULL == tmp) {
+                               log_err ("Query \"%s\" not found for server version %i - "
+                                               "please check your configuration.",
+                                               db->queries[j]->name, server_version);
+
+                               if (db->queries_num - j - 1 > 0)
+                                       memmove (db->queries + j, db->queries + j + 1,
+                                                       (db->queries_num - j - 1) * sizeof (*db->queries));
+
+                               --db->queries_num;
+                               --j;
+                               continue;
+                       }
+
+                       db->queries[j] = tmp;
+               }
        }
 
        plugin_register_read ("postgresql", c_psql_read);
@@ -420,7 +623,7 @@ static int c_psql_init (void)
        return 0;
 } /* c_psql_init */
 
-static int config_set (char *name, char **var, const oconfig_item_t *ci)
+static int config_set_s (char *name, char **var, const oconfig_item_t *ci)
 {
        if ((0 != ci->children_num) || (1 != ci->values_num)
                        || (OCONFIG_TYPE_STRING != ci->values[0].type)) {
@@ -431,77 +634,260 @@ static int config_set (char *name, char **var, const oconfig_item_t *ci)
        sfree (*var);
        *var = sstrdup (ci->values[0].value.string);
        return 0;
-} /* config_set */
+} /* config_set_s */
 
-static int c_psql_config_database (oconfig_item_t *ci)
+static int config_set_i (char *name, int *var, const oconfig_item_t *ci)
 {
-       c_psql_database_t *db;
+       if ((0 != ci->children_num) || (1 != ci->values_num)
+                       || (OCONFIG_TYPE_NUMBER != ci->values[0].type)) {
+               log_err ("%s expects a single number argument.", name);
+               return 1;
+       }
 
-       int i;
+       *var = (int)ci->values[0].value.number;
+       return 0;
+} /* config_set_i */
 
-       if ((1 != ci->values_num)
+static int config_set_param (c_psql_query_t *query, const oconfig_item_t *ci)
+{
+       c_psql_param_t param;
+       char          *param_str;
+
+       if ((0 != ci->children_num) || (1 != ci->values_num)
                        || (OCONFIG_TYPE_STRING != ci->values[0].type)) {
-               log_err ("<Database> expects a single string argument.");
+               log_err ("Param expects a single string argument.");
                return 1;
        }
 
-       ++databases_num;
-       if (NULL == (databases = (c_psql_database_t *)realloc (databases,
-                               databases_num * sizeof (*databases)))) {
+       param_str = ci->values[0].value.string;
+       if (0 == strcasecmp (param_str, "hostname"))
+               param = C_PSQL_PARAM_HOST;
+       else if (0 == strcasecmp (param_str, "database"))
+               param = C_PSQL_PARAM_DB;
+       else if (0 == strcasecmp (param_str, "username"))
+               param = C_PSQL_PARAM_USER;
+       else {
+               log_err ("Invalid parameter \"%s\".", param_str);
+               return 1;
+       }
+
+       ++query->params_num;
+       if (NULL == (query->params = (c_psql_param_t *)realloc (query->params,
+                               query->params_num * sizeof (*query->params)))) {
                log_err ("Out of memory.");
                exit (5);
        }
 
-       db = databases + (databases_num - 1);
+       query->params[query->params_num - 1] = param;
+       return 0;
+} /* config_set_param */
 
-       db->conn = NULL;
+static int config_set_column (c_psql_query_t *query, const oconfig_item_t *ci)
+{
+       c_psql_col_t *col;
 
-       db->conn_complaint.last     = 0;
-       db->conn_complaint.interval = 0;
+       int i;
 
-       db->database   = sstrdup (ci->values[0].value.string);
-       db->host       = NULL;
-       db->port       = NULL;
-       db->user       = NULL;
-       db->password   = NULL;
+       if ((0 != ci->children_num)
+                       || (1 > ci->values_num) || (2 < ci->values_num)) {
+               log_err ("Column expects either one or two arguments.");
+               return 1;
+       }
 
-       db->sslmode    = NULL;
+       for (i = 0; i < ci->values_num; ++i) {
+               if (OCONFIG_TYPE_STRING != ci->values[i].type) {
+                       log_err ("Column expects either one or two string arguments.");
+                       return 1;
+               }
+       }
 
-       db->krbsrvname = NULL;
+       ++query->cols_num;
+       if (NULL == (query->cols = (c_psql_col_t *)realloc (query->cols,
+                               query->cols_num * sizeof (*query->cols)))) {
+               log_err ("Out of memory.");
+               exit (5);
+       }
 
-       db->service    = NULL;
+       col = query->cols + query->cols_num - 1;
+
+       col->ds_type = -1;
+
+       col->type = sstrdup (ci->values[0].value.string);
+       col->type_instance = (2 == ci->values_num)
+               ? sstrdup (ci->values[1].value.string) : NULL;
+       return 0;
+} /* config_set_column */
+
+static int set_query (c_psql_database_t *db, const char *name)
+{
+       c_psql_query_t *query;
+
+       query = c_psql_query_get (name, -1);
+       if (NULL == query) {
+               log_err ("Query \"%s\" not found - please check your configuration.",
+                               name);
+               return 1;
+       }
+
+       ++db->queries_num;
+       if (NULL == (db->queries = (c_psql_query_t **)realloc (db->queries,
+                               db->queries_num * sizeof (*db->queries)))) {
+               log_err ("Out of memory.");
+               exit (5);
+       }
+
+       if (query->params_num > db->max_params_num)
+               db->max_params_num = query->params_num;
+
+       db->queries[db->queries_num - 1] = query;
+       return 0;
+} /* set_query */
+
+static int config_set_query (c_psql_database_t *db, const oconfig_item_t *ci)
+{
+       if ((0 != ci->children_num) || (1 != ci->values_num)
+                       || (OCONFIG_TYPE_STRING != ci->values[0].type)) {
+               log_err ("Query expects a single string argument.");
+               return 1;
+       }
+       return set_query (db, ci->values[0].value.string);
+} /* config_set_query */
+
+static int c_psql_config_query (oconfig_item_t *ci)
+{
+       c_psql_query_t *query;
+
+       int i;
+
+       if ((1 != ci->values_num)
+                       || (OCONFIG_TYPE_STRING != ci->values[0].type)) {
+               log_err ("<Query> expects a single string argument.");
+               return 1;
+       }
+
+       query = c_psql_query_new (ci->values[0].value.string);
+
+       for (i = 0; i < ci->children_num; ++i) {
+               oconfig_item_t *c = ci->children + i;
+
+               if (0 == strcasecmp (c->key, "Query"))
+                       config_set_s ("Query", &query->query, c);
+               else if (0 == strcasecmp (c->key, "Param"))
+                       config_set_param (query, c);
+               else if (0 == strcasecmp (c->key, "Column"))
+                       config_set_column (query, c);
+               else if (0 == strcasecmp (c->key, "MinPGVersion"))
+                       config_set_i ("MinPGVersion", &query->min_pg_version, c);
+               else if (0 == strcasecmp (c->key, "MaxPGVersion"))
+                       config_set_i ("MaxPGVersion", &query->max_pg_version, c);
+               else
+                       log_warn ("Ignoring unknown config key \"%s\".", c->key);
+       }
+
+       for (i = 0; i < queries_num - 1; ++i) {
+               c_psql_query_t *q = queries + i;
+
+               if ((0 == strcasecmp (q->name, query->name))
+                               && (q->min_pg_version <= query->max_pg_version)
+                               && (query->min_pg_version <= q->max_pg_version)) {
+                       log_err ("Ignoring redefinition (with overlapping version ranges) "
+                                       "of query \"%s\".", query->name);
+                       c_psql_query_delete (query);
+                       --queries_num;
+                       return 1;
+               }
+       }
+
+       if (query->min_pg_version > query->max_pg_version) {
+               log_err ("Query \"%s\": MinPGVersion > MaxPGVersion.",
+                               query->name);
+               c_psql_query_delete (query);
+               --queries_num;
+               return 1;
+       }
+
+       if (NULL == query->query) {
+               log_err ("Query \"%s\" does not include an SQL query string - "
+                               "please check your configuration.", query->name);
+               c_psql_query_delete (query);
+               --queries_num;
+               return 1;
+       }
+       return 0;
+} /* c_psql_config_query */
+
+static int c_psql_config_database (oconfig_item_t *ci)
+{
+       c_psql_database_t *db;
+
+       int i;
+
+       if ((1 != ci->values_num)
+                       || (OCONFIG_TYPE_STRING != ci->values[0].type)) {
+               log_err ("<Database> expects a single string argument.");
+               return 1;
+       }
+
+       db = c_psql_database_new (ci->values[0].value.string);
 
        for (i = 0; i < ci->children_num; ++i) {
                oconfig_item_t *c = ci->children + i;
 
                if (0 == strcasecmp (c->key, "Host"))
-                       config_set ("Host", &db->host, c);
+                       config_set_s ("Host", &db->host, c);
                else if (0 == strcasecmp (c->key, "Port"))
-                       config_set ("Port", &db->port, c);
+                       config_set_s ("Port", &db->port, c);
                else if (0 == strcasecmp (c->key, "User"))
-                       config_set ("User", &db->user, c);
+                       config_set_s ("User", &db->user, c);
                else if (0 == strcasecmp (c->key, "Password"))
-                       config_set ("Password", &db->password, c);
+                       config_set_s ("Password", &db->password, c);
                else if (0 == strcasecmp (c->key, "SSLMode"))
-                       config_set ("SSLMode", &db->sslmode, c);
+                       config_set_s ("SSLMode", &db->sslmode, c);
                else if (0 == strcasecmp (c->key, "KRBSrvName"))
-                       config_set ("KRBSrvName", &db->krbsrvname, c);
+                       config_set_s ("KRBSrvName", &db->krbsrvname, c);
                else if (0 == strcasecmp (c->key, "Service"))
-                       config_set ("Service", &db->service, c);
+                       config_set_s ("Service", &db->service, c);
+               else if (0 == strcasecmp (c->key, "Query"))
+                       config_set_query (db, c);
                else
                        log_warn ("Ignoring unknown config key \"%s\".", c->key);
        }
+
+       if (NULL == db->queries) {
+               for (i = 0; i < def_queries_num; ++i)
+                       set_query (db, def_queries[i]);
+       }
        return 0;
 }
 
 static int c_psql_config (oconfig_item_t *ci)
 {
+       static int have_def_config = 0;
+
        int i;
 
+       if (0 == have_def_config) {
+               oconfig_item_t *c;
+
+               have_def_config = 1;
+
+               c = oconfig_parse_file (C_PSQL_DEFAULT_CONF);
+               if (NULL == c)
+                       log_err ("Failed to read default config ("C_PSQL_DEFAULT_CONF").");
+               else
+                       c_psql_config (c);
+
+               if (NULL == queries)
+                       log_err ("Default config ("C_PSQL_DEFAULT_CONF") did not define "
+                                       "any queries - please check your installation.");
+       }
+
        for (i = 0; i < ci->children_num; ++i) {
                oconfig_item_t *c = ci->children + i;
 
-               if (0 == strcasecmp (c->key, "Database"))
+               if (0 == strcasecmp (c->key, "Query"))
+                       c_psql_config_query (c);
+               else if (0 == strcasecmp (c->key, "Database"))
                        c_psql_config_database (c);
                else
                        log_warn ("Ignoring unknown config key \"%s\".", c->key);