pg_dump, pg_dumpall y psql.PostgreSQL, o simplemente "Postgres", es un sistema de gestión de bases de datos orientado a objetos y relacional (ORDBMS) que hace énfasis en la extensibilidad y conformidad con los estándares. Está liberado bajo la licencia free/open source PostgreSQL, similar a la licencia MIT. PostgreSQL está desarrollado por el Grupo de Desarrollo Global de PostgreSQL, el cual consiste en un grupo de voluntarios empleados y supervisados por empresas como Red Hat y EnterpriseDB.
PostgreSQL implementa la mayor parte del estándar SQL:2011, cumple con las propiedades ACID (Atomicity, Consistency, Isolation, Durability), es completamente transaccional (incluyendo todas las sentencias DDL, Data Definition Language), posee vistas extensibles actualizables, tipos de datos, operadores, índices, funciones, agregación, incluye un lenguaje procedural, y tiene un gran número de extensiones de terceros.
PostgreSQL funciona en la mayoría de los sistemas operativos incluyendo GNU/Linux, FreeBSD, Solaris, Microsoft Windows y MacOS X. La gran mayoría de distribuciones GNU/Linux disponen de PostgreSQL en sus repositorios.
El sitio oficial del proyecto es www.postgresql.org.
Este es mi primer artículo dedicado a Postgres, por ello voy a arrancar con algo sencillo: cómo exportar y restaurar bases de datos Postgres desde línea de comandos.
Si se desea exportar una base de datos, ya sea para generar una copia de respaldo (backup) como para importar en otro servidor, es posible utilizar la herramienta
pg_dump,
la cual vuelca una base de datos como una secuencia de instrucciones
SQL en formato de texto plano (al igual que la herramienta mysqldump
de MySQL). Por ejemplo, si se desea exportar la base de datos "mibd" al
archivo "pg_mibd.sql" utilizando el usuario "postgres", ejecutar:# pg_dump -U postgres -f pg_mibd.sql mibd
O también:
# pg_dump -U postgres mibd > pg_mibd.sql
Para obtener ayuda sobre
pg_dump, ejecutar:# pg_dump --help pg_dump dumps a database as a text file or to other formats.
Usage:
pg_dump [OPTION]... [DBNAME]
General options:
-f, --file=FILENAME output file or directory name
-F, --format=c|d|t|p output file format (custom, directory, tar,
plain text (default))
-j, --jobs=NUM use this many parallel jobs to dump
-v, --verbose verbose mode
-V, --version output version information, then exit
-Z, --compress=0-9 compression level for compressed formats
--lock-wait-timeout=TIMEOUT fail after waiting TIMEOUT for a table lock
-?, --help show this help, then exit
Options controlling the output content:
-a, --data-only dump only the data, not the schema
-b, --blobs include large objects in dump
-c, --clean clean (drop) database objects before recreating
-C, --create include commands to create database in dump
-E, --encoding=ENCODING dump the data in encoding ENCODING
-n, --schema=SCHEMA dump the named schema(s) only
-N, --exclude-schema=SCHEMA do NOT dump the named schema(s)
-o, --oids include OIDs in dump
-O, --no-owner skip restoration of object ownership in
plain-text format
-s, --schema-only dump only the schema, no data
-S, --superuser=NAME superuser user name to use in plain-text format
-t, --table=TABLE dump the named table(s) only
-T, --exclude-table=TABLE do NOT dump the named table(s)
-x, --no-privileges do not dump privileges (grant/revoke)
--binary-upgrade for use by upgrade utilities only
--column-inserts dump data as INSERT commands with column names
--disable-dollar-quoting disable dollar quoting, use SQL standard quoting
--disable-triggers disable triggers during data-only restore
--exclude-table-data=TABLE do NOT dump data for the named table(s)
--inserts dump data as INSERT commands, rather than COPY
--no-security-labels do not dump security label assignments
--no-synchronized-snapshots do not use synchronized snapshots in parallel jobs
--no-tablespaces do not dump tablespace assignments
--no-unlogged-table-data do not dump unlogged table data
--quote-all-identifiers quote all identifiers, even if not key words
--section=SECTION dump named section (pre-data, data, or post-data)
--serializable-deferrable wait until the dump can run without anomalies
--use-set-session-authorization
use SET SESSION AUTHORIZATION commands instead of
ALTER OWNER commands to set ownership
Connection options:
-d, --dbname=DBNAME database to dump
-h, --host=HOSTNAME database server host or socket directory
-p, --port=PORT database server port number
-U, --username=NAME connect as specified database user
-w, --no-password never prompt for password
-W, --password force password prompt (should happen automatically)
--role=ROLENAME do SET ROLE before dump
If no database name is supplied, then the PGDATABASE environment
variable value is used.
Report bugs to <pgsql-bugs@postgresql.org>.
Si en cambio se desean exportar todas las bases de datos de un servidor PostgreSQL, utilizar la herramienta
pg_dumpall:# pg_dumpall -U postgres > pg_todo.sql
Para obtener ayuda sobre
pg_dumpall, ejecutar:# pg_dumpall --help
pg_dumpall extracts a PostgreSQL database cluster into an SQL script file.
Usage:
pg_dumpall [OPTION]...
General options:
-f, --file=FILENAME output file name
-V, --version output version information, then exit
--lock-wait-timeout=TIMEOUT fail after waiting TIMEOUT for a table lock
-?, --help show this help, then exit
Options controlling the output content:
-a, --data-only dump only the data, not the schema
-c, --clean clean (drop) databases before recreating
-g, --globals-only dump only global objects, no databases
-o, --oids include OIDs in dump
-O, --no-owner skip restoration of object ownership
-r, --roles-only dump only roles, no databases or tablespaces
-s, --schema-only dump only the schema, no data
-S, --superuser=NAME superuser user name to use in the dump
-t, --tablespaces-only dump only tablespaces, no databases or roles
-x, --no-privileges do not dump privileges (grant/revoke)
--binary-upgrade for use by upgrade utilities only
--column-inserts dump data as INSERT commands with column names
--disable-dollar-quoting disable dollar quoting, use SQL standard quoting
--disable-triggers disable triggers during data-only restore
--inserts dump data as INSERT commands, rather than COPY
--no-security-labels do not dump security label assignments
--no-tablespaces do not dump tablespace assignments
--no-unlogged-table-data do not dump unlogged table data
--quote-all-identifiers quote all identifiers, even if not key words
--use-set-session-authorization
use SET SESSION AUTHORIZATION commands instead of
ALTER OWNER commands to set ownership
Connection options:
-d, --dbname=CONNSTR connect using connection string
-h, --host=HOSTNAME database server host or socket directory
-l, --database=DBNAME alternative default database
-p, --port=PORT database server port number
-U, --username=NAME connect as specified database user
-w, --no-password never prompt for password
-W, --password force password prompt (should happen automatically)
--role=ROLENAME do SET ROLE before dump
If -f/--file is not used, then the SQL script will be written to the standard
output.
Report bugs to <pgsql-bugs@postgresql.org>.
Para importar o restaurar un volcado de bases de datos Postgres desde línea de comandos, se debe utilizar la herramienta
psql,
la cual funciona como terminal interactiva contra servidores
PostgreSQL. Por ejemplo, si se desea restaurar el volcado del archivo
"pg_mibd.sql" (utilizando el usuario "postgres") guardando un log en el
archivo "pg_mibd.log", ejecutar:# psql -U postgres < pg_mibd.sql > pg_mibd.log 2>&1
Luego es posible buscar errores en el log mediante:
# grep -i error pg_mibd.log
Para obtener ayuda sobre
psql, ejecutar:# psql --help
psql is the PostgreSQL interactive terminal.
Usage:
psql [OPTION]... [DBNAME [USERNAME]]
General options:
-c, --command=COMMAND run only single command (SQL or internal) and exit
-d, --dbname=DBNAME database name to connect to (default: "root")
-f, --file=FILENAME execute commands from file, then exit
-l, --list list available databases, then exit
-v, --set=, --variable=NAME=VALUE
set psql variable NAME to VALUE
-V, --version output version information, then exit
-X, --no-psqlrc do not read startup file (~/.psqlrc)
-1 ("one"), --single-transaction
execute as a single transaction (if non-interactive)
-?, --help show this help, then exit
Input and output options:
-a, --echo-all echo all input from script
-e, --echo-queries echo commands sent to server
-E, --echo-hidden display queries that internal commands generate
-L, --log-file=FILENAME send session log to file
-n, --no-readline disable enhanced command line editing (readline)
-o, --output=FILENAME send query results to file (or |pipe)
-q, --quiet run quietly (no messages, only query output)
-s, --single-step single-step mode (confirm each query)
-S, --single-line single-line mode (end of line terminates SQL command)
Output format options:
-A, --no-align unaligned table output mode
-F, --field-separator=STRING
set field separator (default: "|")
-H, --html HTML table output mode
-P, --pset=VAR[=ARG] set printing option VAR to ARG (see \pset command)
-R, --record-separator=STRING
set record separator (default: newline)
-t, --tuples-only print rows only
-T, --table-attr=TEXT set HTML table tag attributes (e.g., width, border)
-x, --expanded turn on expanded table output
-z, --field-separator-zero
set field separator to zero byte
-0, --record-separator-zero
set record separator to zero byte
Connection options:
-h, --host=HOSTNAME database server host or socket directory (default: "local socket")
-p, --port=PORT database server port (default: "5432")
-U, --username=USERNAME database user name (default: "root")
-w, --no-password never prompt for password
-W, --password force password prompt (should happen automatically)
For more information, type "\?" (for internal commands) or "\help" (for SQL
commands) from within psql, or consult the psql section in the PostgreSQL
documentation.
Report bugs to <pgsql-bugs@postgresql.org>.
pgAdmin
Para quienes sientan temor de las herramientas de línea de comandos existe un cliente GUI llamado "pgAdmin".Una vez instalado, ejecutar
pgadmin3:
Fuente: http://www.linuxito.com