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Create an user mapping (so that different users could do be allowed to perform different operations on the remote tables).NB! The FDW also supports writing/changing data and transactions! Full documentation here. True, in older Postgres versions the plans were not always too optimal but recent 9.6 version got a lot of attention in that area. Basically what you get here is a permanent “symlink / synonym” to a table/view on another database, with the benefit that the local Postgres database (where the user is connected) already has the column details on the table – most importantly size and data distribution statistics, so that it can figure out better execution plans. On board since 9.3, the Postgres foreign-data wrapper (postgres_fdw extension, available in “contrib”) is an improvement over dblink and is well suitable for more permanent data crunching and one could even build complex sharding/scaling architectures on top of it with the introduction of “foreign table inheritance” in 9.6. Pros: easiest setup possible, flexibility on connecting to X amount of Postgres DBsĬons: SQLs could get ugly for multiple joins, possible performance issues for bigger datasets, basic transaction support The Postgres foreign-data wrapper
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SELECT column1, column2, columnN FROM table_name The basic syntax of SELECT statement is as follows − These result tables are called result-sets. PostgreSQL SELECT statement is used to fetch the data from a database table, which returns data in the form of result table.