PG如何获取系统视图/函数对应的源码

pg13@cnndr4pptliot-> psql bill bill -Epsql (13beta3)Type 'help' for help.bill@bill=>\d+ pg_stat_database                                    View 'pg_catalog.pg_stat_database'        Column         |           Type           | Collation | Nullable | Default | Storage | Description-----------------------+--------------------------+-----------+----------+---------+---------+------------- datid                 | oid                      |           |          |         | plain   | datname               | name                     |           |          |         | plain   | numbackends           | integer                  |           |          |         | plain   | xact_commit           | bigint                   |           |          |         | plain   | xact_rollback         | bigint                   |           |          |         | plain   | blks_read             | bigint                   |           |          |         | plain   | blks_hit              | bigint                   |           |          |         | plain   | tup_returned          | bigint                   |           |          |         | plain   | tup_fetched           | bigint                   |           |          |         | plain   | tup_inserted          | bigint                   |           |          |         | plain   | tup_updated           | bigint                   |           |          |         | plain   | tup_deleted           | bigint                   |           |          |         | plain   | conflicts             | bigint                   |           |          |         | plain   | temp_files            | bigint                   |           |          |         | plain   | temp_bytes            | bigint                   |           |          |         | plain   | deadlocks             | bigint                   |           |          |         | plain   | checksum_failures     | bigint                   |           |          |         | plain   | checksum_last_failure | timestamp with time zone |           |          |         | plain   | blk_read_time         | double precision         |           |          |         | plain   | blk_write_time        | double precision         |           |          |         | plain   | stats_reset           | timestamp with time zone |           |          |         | plain   |View definition: SELECT d.oid AS datid,    d.datname,        CASE            WHEN d.oid = 0::oid THEN 0            ELSE pg_stat_get_db_numbackends(d.oid)        END AS numbackends,    pg_stat_get_db_xact_commit(d.oid) AS xact_commit,    pg_stat_get_db_xact_rollback(d.oid) AS xact_rollback,    pg_stat_get_db_blocks_fetched(d.oid) - pg_stat_get_db_blocks_hit(d.oid) AS blks_read,    pg_stat_get_db_blocks_hit(d.oid) AS blks_hit,    pg_stat_get_db_tuples_returned(d.oid) AS tup_returned,    pg_stat_get_db_tuples_fetched(d.oid) AS tup_fetched,    pg_stat_get_db_tuples_inserted(d.oid) AS tup_inserted,    pg_stat_get_db_tuples_updated(d.oid) AS tup_updated,    pg_stat_get_db_tuples_deleted(d.oid) AS tup_deleted,    pg_stat_get_db_conflict_all(d.oid) AS conflicts,    pg_stat_get_db_temp_files(d.oid) AS temp_files,    pg_stat_get_db_temp_bytes(d.oid) AS temp_bytes,    pg_stat_get_db_deadlocks(d.oid) AS deadlocks,    pg_stat_get_db_checksum_failures(d.oid) AS checksum_failures,    pg_stat_get_db_checksum_last_failure(d.oid) AS checksum_last_failure,    pg_stat_get_db_blk_read_time(d.oid) AS blk_read_time,    pg_stat_get_db_blk_write_time(d.oid) AS blk_write_time,    pg_stat_get_db_stat_reset_time(d.oid) AS stats_reset   FROM ( SELECT 0 AS oid,            NULL::name AS datname        UNION ALL         SELECT pg_database.oid,            pg_database.datname           FROM pg_database) d;
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bill@bill=>\df+ pg_stat_get_db_tuples_returnedList of functions-[ RECORD 1 ]-------+-----------------------------------------Schema              | pg_catalogName                | pg_stat_get_db_tuples_returnedResult data type    | bigintArgument data types | oidType                | funcVolatility          | stableParallel            | restrictedOwner               | postgresSecurity            | invokerAccess privileges   |Language            | internalSource code         | pg_stat_get_db_tuples_returnedDescription         | statistics: tuples returned for database
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Datumpg_stat_get_tuples_returned(PG_FUNCTION_ARGS){    Oid            relid = PG_GETARG_OID(0);    int64        result;    PgStat_StatTabEntry *tabentry;    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)        result = 0;    else        result = (int64) (tabentry->tuples_returned);    PG_RETURN_INT64(result);}
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