How do I discover the structure of a PostgreSQL database?

Question

I need to write a script that will output data from a PostgreSQL database that I do not know the structure of. What query will return the names of all tables in a database? And what query will list the names of all columns in a table?

Answer 1

The database query tool psql, part of the PostgreSQL distribution, provides table description functionality.

# psql postgres postgres psql (9.1.0) Type "help" for help.  postgres=# -- list all tables: postgres=# \d            List of relations  Schema |   Name    | Type  |  Owner    --------+-----------+-------+----------  public | my_table  | table | postgres  public | my_table2 | table | postgres (2 rows)   postgres=# -- describe table: postgres=# \d my_table    Table "public.my_table"  Column |  Type   | Modifiers  --------+---------+-----------  col1   | integer |   col2   | text    |  

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The rest of the psql commands you can get with \?:

postgres=#   \? General   \copyright             show PostgreSQL usage and distribution terms   \g [FILE] or ;         execute query (and send results to file or |pipe)   \h [NAME]              help on syntax of SQL commands, * for all commands   \q                     quit psql  Query Buffer   \e [FILE] [LINE]       edit the query buffer (or file) with external editor   \ef [FUNCNAME [LINE]]  edit function definition with external editor   \p                     show the contents of the query buffer   \r                     reset (clear) the query buffer   \s [FILE]              display history or save it to file   \w FILE                write query buffer to file  Input/Output   \copy ...              perform SQL COPY with data stream to the client host   \echo [STRING]         write string to standard output   \i FILE                execute commands from file   \o [FILE]              send all query results to file or |pipe   \qecho [STRING]        write string to query output stream (see \o)  Informational   (options: S = show system objects, + = additional detail)   \d[S+]                 list tables, views, and sequences   \d[S+]  NAME           describe table, view, sequence, or index   \da[S]  [PATTERN]      list aggregates   \db[+]  [PATTERN]      list tablespaces   \dc[S]  [PATTERN]      list conversions   \dC     [PATTERN]      list casts   \dd[S]  [PATTERN]      show comments on objects   \ddp    [PATTERN]      list default privileges   \dD[S]  [PATTERN]      list domains   \det[+] [PATTERN]      list foreign tables   \des[+] [PATTERN]      list foreign servers   \deu[+] [PATTERN]      list user mappings   \dew[+] [PATTERN]      list foreign-data wrappers   \df[antw][S+] [PATRN]  list [only agg/normal/trigger/window] functions   \dF[+]  [PATTERN]      list text search configurations   \dFd[+] [PATTERN]      list text search dictionaries   \dFp[+] [PATTERN]      list text search parsers   \dFt[+] [PATTERN]      list text search templates   \dg[+]  [PATTERN]      list roles   \di[S+] [PATTERN]      list indexes   \dl                    list large objects, same as \lo_list   \dL[S+] [PATTERN]      list procedural languages   \dn[S+] [PATTERN]      list schemas   \do[S]  [PATTERN]      list operators   \dO[S+] [PATTERN]      list collations   \dp     [PATTERN]      list table, view, and sequence access privileges   \drds [PATRN1 [PATRN2]] list per-database role settings   \ds[S+] [PATTERN]      list sequences   \dt[S+] [PATTERN]      list tables   \dT[S+] [PATTERN]      list data types   \du[+]  [PATTERN]      list roles   \dv[S+] [PATTERN]      list views   \dE[S+] [PATTERN]      list foreign tables   \dx[+]  [PATTERN]      list extensions   \l[+]                  list all databases   \sf[+] FUNCNAME        show a function's definition   \z      [PATTERN]      same as \dp  Formatting   \a                     toggle between unaligned and aligned output mode   \C [STRING]            set table title, or unset if none   \f [STRING]            show or set field separator for unaligned query output   \H                     toggle HTML output mode (currently off)   \pset NAME [VALUE]     set table output option                          (NAME := {format|border|expanded|fieldsep|footer|null|                          numericlocale|recordsep|tuples_only|title|tableattr|pager})   \t [on|off]            show only rows (currently off)   \T [STRING]            set HTML <table> tag attributes, or unset if none   \x [on|off]            toggle expanded output (currently off)  Connection   \c[onnect] [DBNAME|- USER|- HOST|- PORT|-]                          connect to new database (currently "postgres")   \encoding [ENCODING]   show or set client encoding   \password [USERNAME]   securely change the password for a user   \conninfo              display information about current connection  Operating System   \cd [DIR]              change the current working directory   \timing [on|off]       toggle timing of commands (currently off)   \! [COMMAND]           execute command in shell or start interactive shell  Variables   \prompt [TEXT] NAME    prompt user to set internal variable   \set [NAME [VALUE]]    set internal variable, or list all if no parameters   \unset NAME            unset (delete) internal variable  Large Objects   \lo_export LOBOID FILE   \lo_import FILE [COMMENT]   \lo_list   \lo_unlink LOBOID      large object operations 

Answer 2

SELECT table_name      FROM information_schema.tables  WHERE table_type = 'BASE TABLE'      AND table_schema NOT IN          ('pg_catalog', 'information_schema');   SELECT column_name      FROM information_schema.columns  WHERE table_name = 'YourTablesName';  

This page has some great information on retrieving information from information_schema: http://www.alberton.info/postgresql_meta_info.html