If connecting Metabase with a postgres directly, Metabase will open 2 cursors and fire the query once. This is the log:
2023-02-14 13:12:34.051 UTC [37165] LOG: execute <unnamed>: SELECT NULL AS TABLE_CAT, n.nspname AS TABLE_SCHEM, c.relname AS TABLE_NAME, CASE n.nspname ~ '^pg_' OR n.nspname = 'information_schema' WHEN true THEN CASE WHEN n.nspname = 'pg_catalog' OR n.nspname = 'information_schema' THEN CASE c.relkind WHEN 'r' THEN 'SYSTEM TABLE' WHEN 'v' THEN 'SYSTEM VIEW' WHEN 'i' THEN 'SYSTEM INDEX' ELSE NULL END WHEN n.nspname = 'pg_toast' THEN CASE c.relkind WHEN 'r' THEN 'SYSTEM TOAST TABLE' WHEN 'i' THEN 'SYSTEM TOAST INDEX' ELSE NULL END ELSE CASE c.relkind WHEN 'r' THEN 'TEMPORARY TABLE' WHEN 'p' THEN 'TEMPORARY TABLE' WHEN 'i' THEN 'TEMPORARY INDEX' WHEN 'S' THEN 'TEMPORARY SEQUENCE' WHEN 'v' THEN 'TEMPORARY VIEW' ELSE NULL END END WHEN false THEN CASE c.relkind WHEN 'r' THEN 'TABLE' WHEN 'p' THEN 'PARTITIONED TABLE' WHEN 'i' THEN 'INDEX' WHEN 'P' then 'PARTITIONED INDEX' WHEN 'S' THEN 'SEQUENCE' WHEN 'v' THEN 'VIEW' WHEN 'c' THEN 'TYPE' WHEN 'f' THEN 'FOREIGN TABLE' WHEN 'm' THEN 'MATERIALIZED VIEW' ELSE NULL END ELSE NULL END AS TABLE_TYPE, d.description AS REMARKS, '' as TYPE_CAT, '' as TYPE_SCHEM, '' as TYPE_NAME, '' AS SELF_REFERENCING_COL_NAME, '' AS REF_GENERATION FROM pg_catalog.pg_namespace n, pg_catalog.pg_class c LEFT JOIN pg_catalog.pg_description d ON (c.oid = d.objoid AND d.objsubid = 0 and d.classoid = 'pg_class'::regclass) WHERE c.relnamespace = n.oid AND n.nspname LIKE 'public' AND c.relname LIKE 'people' AND (false OR ( c.relkind = 'r' AND n.nspname !~ '^pg_' AND n.nspname <> 'information_schema' ) OR ( c.relkind = 'p' AND n.nspname !~ '^pg_' AND n.nspname <> 'information_schema' ) OR ( c.relkind = 'v' AND n.nspname <> 'pg_catalog' AND n.nspname <> 'information_schema' ) OR ( c.relkind = 'm' ) OR ( c.relkind = 'f' ) ) ORDER BY TABLE_TYPE,TABLE_SCHEM,TABLE_NAME
2023-02-14 13:12:34.054 UTC [37165] LOG: execute <unnamed>: SELECT * FROM (SELECT n.nspname,c.relname,a.attname,a.atttypid,a.attnotnull OR (t.typtype = 'd' AND t.typnotnull) AS attnotnull,a.atttypmod,a.attlen,t.typtypmod,row_number() OVER (PARTITION BY a.attrelid ORDER BY a.attnum) AS attnum, nullif(a.attidentity, '') as attidentity,nullif(a.attgenerated, '') as attgenerated,pg_catalog.pg_get_expr(def.adbin, def.adrelid) AS adsrc,dsc.description,t.typbasetype,t.typtype FROM pg_catalog.pg_namespace n JOIN pg_catalog.pg_class c ON (c.relnamespace = n.oid) JOIN pg_catalog.pg_attribute a ON (a.attrelid=c.oid) JOIN pg_catalog.pg_type t ON (a.atttypid = t.oid) LEFT JOIN pg_catalog.pg_attrdef def ON (a.attrelid=def.adrelid AND a.attnum = def.adnum) LEFT JOIN pg_catalog.pg_description dsc ON (c.oid=dsc.objoid AND a.attnum = dsc.objsubid) LEFT JOIN pg_catalog.pg_class dc ON (dc.oid=dsc.classoid AND dc.relname='pg_class') LEFT JOIN pg_catalog.pg_namespace dn ON (dc.relnamespace=dn.oid AND dn.nspname='pg_catalog') WHERE c.relkind in ('r','p','v','f','m') and a.attnum > 0 AND NOT a.attisdropped AND n.nspname LIKE 'public' AND c.relname LIKE 'people') c WHERE true ORDER BY nspname,c.relname,attnum
2023-02-14 13:12:34.062 UTC [37165] LOG: execute <unnamed>: BEGIN READ ONLY
2023-02-14 13:12:34.062 UTC [37165] LOG: execute <unnamed>/C_1: SELECT "id", "address", "email", "password", "name", "city", "longitude", "state", "source", "birth_date", "zip", "latitude", "created_at" FROM "public"."people"
2023-02-14 13:12:34.067 UTC [37165] LOG: execute fetch from <unnamed>/C_1: SELECT "id", "address", "email", "password", "name", "city", "longitude", "state", "source", "birth_date", "zip", "latitude", "created_at" FROM "public"."people"
2023-02-14 13:12:34.072 UTC [37165] LOG: execute fetch from <unnamed>/C_1: SELECT "id", "address", "email", "password", "name", "city", "longitude", "state", "source", "birth_date", "zip", "latitude", "created_at" FROM "public"."people"
2023-02-14 13:18:21.065 UTC [37412] LOG: execute <unnamed>: SET extra_float_digits = 3
2023-02-14 13:18:21.065 UTC [37412] LOG: execute <unnamed>: SET application_name = 'PostgreSQL JDBC Driver'
2023-02-14 13:18:21.067 UTC [37412] LOG: execute <unnamed>: SELECT NULL AS TABLE_CAT, n.nspname AS TABLE_SCHEM, c.relname AS TABLE_NAME, CASE n.nspname ~ '^pg_' OR n.nspname = 'information_schema' WHEN true THEN CASE WHEN n.nspname = 'pg_catalog' OR n.nspname = 'information_schema' THEN CASE c.relkind WHEN 'r' THEN 'SYSTEM TABLE' WHEN 'v' THEN 'SYSTEM VIEW' WHEN 'i' THEN 'SYSTEM INDEX' ELSE NULL END WHEN n.nspname = 'pg_toast' THEN CASE c.relkind WHEN 'r' THEN 'SYSTEM TOAST TABLE' WHEN 'i' THEN 'SYSTEM TOAST INDEX' ELSE NULL END ELSE CASE c.relkind WHEN 'r' THEN 'TEMPORARY TABLE' WHEN 'p' THEN 'TEMPORARY TABLE' WHEN 'i' THEN 'TEMPORARY INDEX' WHEN 'S' THEN 'TEMPORARY SEQUENCE' WHEN 'v' THEN 'TEMPORARY VIEW' ELSE NULL END END WHEN false THEN CASE c.relkind WHEN 'r' THEN 'TABLE' WHEN 'p' THEN 'PARTITIONED TABLE' WHEN 'i' THEN 'INDEX' WHEN 'P' then 'PARTITIONED INDEX' WHEN 'S' THEN 'SEQUENCE' WHEN 'v' THEN 'VIEW' WHEN 'c' THEN 'TYPE' WHEN 'f' THEN 'FOREIGN TABLE' WHEN 'm' THEN 'MATERIALIZED VIEW' ELSE NULL END ELSE NULL END AS TABLE_TYPE, d.description AS REMARKS, '' as TYPE_CAT, '' as TYPE_SCHEM, '' as TYPE_NAME, '' AS SELF_REFERENCING_COL_NAME, '' AS REF_GENERATION FROM pg_catalog.pg_namespace n, pg_catalog.pg_class c LEFT JOIN pg_catalog.pg_description d ON (c.oid = d.objoid AND d.objsubid = 0 and d.classoid = 'pg_class'::regclass) WHERE c.relnamespace = n.oid AND n.nspname LIKE 'public' AND c.relname LIKE 'people' AND (false OR ( c.relkind = 'r' AND n.nspname !~ '^pg_' AND n.nspname <> 'information_schema' ) OR ( c.relkind = 'p' AND n.nspname !~ '^pg_' AND n.nspname <> 'information_schema' ) OR ( c.relkind = 'v' AND n.nspname <> 'pg_catalog' AND n.nspname <> 'information_schema' ) OR ( c.relkind = 'm' ) OR ( c.relkind = 'f' ) ) ORDER BY TABLE_TYPE,TABLE_SCHEM,TABLE_NAME
2023-02-14 13:18:21.069 UTC [37412] LOG: execute <unnamed>: SELECT * FROM (SELECT n.nspname,c.relname,a.attname,a.atttypid,a.attnotnull OR (t.typtype = 'd' AND t.typnotnull) AS attnotnull,a.atttypmod,a.attlen,t.typtypmod,row_number() OVER (PARTITION BY a.attrelid ORDER BY a.attnum) AS attnum, nullif(a.attidentity, '') as attidentity,nullif(a.attgenerated, '') as attgenerated,pg_catalog.pg_get_expr(def.adbin, def.adrelid) AS adsrc,dsc.description,t.typbasetype,t.typtype FROM pg_catalog.pg_namespace n JOIN pg_catalog.pg_class c ON (c.relnamespace = n.oid) JOIN pg_catalog.pg_attribute a ON (a.attrelid=c.oid) JOIN pg_catalog.pg_type t ON (a.atttypid = t.oid) LEFT JOIN pg_catalog.pg_attrdef def ON (a.attrelid=def.adrelid AND a.attnum = def.adnum) LEFT JOIN pg_catalog.pg_description dsc ON (c.oid=dsc.objoid AND a.attnum = dsc.objsubid) LEFT JOIN pg_catalog.pg_class dc ON (dc.oid=dsc.classoid AND dc.relname='pg_class') LEFT JOIN pg_catalog.pg_namespace dn ON (dc.relnamespace=dn.oid AND dn.nspname='pg_catalog') WHERE c.relkind in ('r','p','v','f','m') and a.attnum > 0 AND NOT a.attisdropped AND n.nspname LIKE 'public' AND c.relname LIKE 'people') c WHERE true ORDER BY nspname,c.relname,attnum
2023-02-14 13:18:21.090 UTC [37412] LOG: execute <unnamed>: BEGIN READ ONLY
2023-02-14 13:18:21.091 UTC [37412] LOG: execute <unnamed>/C_1: SELECT "id", "address", "email", "password", "name", "city", "longitude", "state", "source", "birth_date", "zip", "latitude", "created_at" FROM "public"."people"
2023-02-14 13:18:21.096 UTC [37412] LOG: execute fetch from <unnamed>/C_1: SELECT "id", "address", "email", "password", "name", "city", "longitude", "state", "source", "birth_date", "zip", "latitude", "created_at" FROM "public"."people"
2023-02-14 13:18:21.101 UTC [37412] LOG: execute fetch from <unnamed>/C_1: SELECT "id", "address", "email", "password", "name", "city", "longitude", "state", "source", "birth_date", "zip", "latitude", "created_at" FROM "public"."people"
2023-02-14 13:18:21.382 UTC [37413] LOG: execute <unnamed>: SET extra_float_digits = 3
2023-02-14 13:18:21.382 UTC [37413] LOG: execute <unnamed>: SET application_name = 'PostgreSQL JDBC Driver'
2023-02-14 13:18:21.385 UTC [37413] LOG: execute <unnamed>: SELECT NULL AS TABLE_CAT, n.nspname AS TABLE_SCHEM, c.relname AS TABLE_NAME, CASE n.nspname ~ '^pg_' OR n.nspname = 'information_schema' WHEN true THEN CASE WHEN n.nspname = 'pg_catalog' OR n.nspname = 'information_schema' THEN CASE c.relkind WHEN 'r' THEN 'SYSTEM TABLE' WHEN 'v' THEN 'SYSTEM VIEW' WHEN 'i' THEN 'SYSTEM INDEX' ELSE NULL END WHEN n.nspname = 'pg_toast' THEN CASE c.relkind WHEN 'r' THEN 'SYSTEM TOAST TABLE' WHEN 'i' THEN 'SYSTEM TOAST INDEX' ELSE NULL END ELSE CASE c.relkind WHEN 'r' THEN 'TEMPORARY TABLE' WHEN 'p' THEN 'TEMPORARY TABLE' WHEN 'i' THEN 'TEMPORARY INDEX' WHEN 'S' THEN 'TEMPORARY SEQUENCE' WHEN 'v' THEN 'TEMPORARY VIEW' ELSE NULL END END WHEN false THEN CASE c.relkind WHEN 'r' THEN 'TABLE' WHEN 'p' THEN 'PARTITIONED TABLE' WHEN 'i' THEN 'INDEX' WHEN 'P' then 'PARTITIONED INDEX' WHEN 'S' THEN 'SEQUENCE' WHEN 'v' THEN 'VIEW' WHEN 'c' THEN 'TYPE' WHEN 'f' THEN 'FOREIGN TABLE' WHEN 'm' THEN 'MATERIALIZED VIEW' ELSE NULL END ELSE NULL END AS TABLE_TYPE, d.description AS REMARKS, '' as TYPE_CAT, '' as TYPE_SCHEM, '' as TYPE_NAME, '' AS SELF_REFERENCING_COL_NAME, '' AS REF_GENERATION FROM pg_catalog.pg_namespace n, pg_catalog.pg_class c LEFT JOIN pg_catalog.pg_description d ON (c.oid = d.objoid AND d.objsubid = 0 and d.classoid = 'pg_class'::regclass) WHERE c.relnamespace = n.oid AND n.nspname LIKE 'public' AND c.relname LIKE 'people' AND (false OR ( c.relkind = 'r' AND n.nspname !~ '^pg_' AND n.nspname <> 'information_schema' ) OR ( c.relkind = 'p' AND n.nspname !~ '^pg_' AND n.nspname <> 'information_schema' ) OR ( c.relkind = 'v' AND n.nspname <> 'pg_catalog' AND n.nspname <> 'information_schema' ) OR ( c.relkind = 'm' ) OR ( c.relkind = 'f' ) ) ORDER BY TABLE_TYPE,TABLE_SCHEM,TABLE_NAME
2023-02-14 13:18:21.387 UTC [37413] LOG: execute <unnamed>: SELECT * FROM (SELECT n.nspname,c.relname,a.attname,a.atttypid,a.attnotnull OR (t.typtype = 'd' AND t.typnotnull) AS attnotnull,a.atttypmod,a.attlen,t.typtypmod,row_number() OVER (PARTITION BY a.attrelid ORDER BY a.attnum) AS attnum, nullif(a.attidentity, '') as attidentity,nullif(a.attgenerated, '') as attgenerated,pg_catalog.pg_get_expr(def.adbin, def.adrelid) AS adsrc,dsc.description,t.typbasetype,t.typtype FROM pg_catalog.pg_namespace n JOIN pg_catalog.pg_class c ON (c.relnamespace = n.oid) JOIN pg_catalog.pg_attribute a ON (a.attrelid=c.oid) JOIN pg_catalog.pg_type t ON (a.atttypid = t.oid) LEFT JOIN pg_catalog.pg_attrdef def ON (a.attrelid=def.adrelid AND a.attnum = def.adnum) LEFT JOIN pg_catalog.pg_description dsc ON (c.oid=dsc.objoid AND a.attnum = dsc.objsubid) LEFT JOIN pg_catalog.pg_class dc ON (dc.oid=dsc.classoid AND dc.relname='pg_class') LEFT JOIN pg_catalog.pg_namespace dn ON (dc.relnamespace=dn.oid AND dn.nspname='pg_catalog') WHERE c.relkind in ('r','p','v','f','m') and a.attnum > 0 AND NOT a.attisdropped AND n.nspname LIKE 'public' AND c.relname LIKE 'people') c WHERE true ORDER BY nspname,c.relname,attnum
2023-02-14 13:18:21.394 UTC [37413] LOG: execute <unnamed>: BEGIN READ ONLY
2023-02-14 13:18:21.394 UTC [37413] LOG: execute <unnamed>/C_1: SELECT "id", "address", "email", "password", "name", "city", "longitude", "state", "source", "birth_date", "zip", "latitude", "created_at" FROM "public"."people"
2023-02-14 13:18:21.399 UTC [37413] LOG: execute fetch from <unnamed>/C_1: SELECT "id", "address", "email", "password", "name", "city", "longitude", "state", "source", "birth_date", "zip", "latitude", "created_at" FROM "public"."people"
2023-02-14 13:18:21.404 UTC [37413] LOG: execute fetch from <unnamed>/C_1: SELECT "id", "address", "email", "password", "name", "city", "longitude", "state", "source", "birth_date", "zip", "latitude", "created_at" FROM "public"."people"
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