Database Reference
In-Depth Information
• Materialized view (see “Materialized Views” on page 123 ) was unveiled. You can now
persist data into frequently used views to avoid making repeated retrieval calls for
slow queries.
• Views are updatable automatically. You can use an UPDATE statement on a single
view and have it update the underlying tables, without needing to create triggers or
rules.
• Views now accommodate recursive common table expressions (CTEs).
• More JSON constructors and extractors are available. See “JSON” on page 96 .
• Indexed regular-expression search is enabled.
• A 64-bit large object API allows storage of objects that are terabytes in size. The
previous limit was a mere 2 GB.
• The postgres_fdw driver, introduced in “Querying Other PostgreSQL Servers” on
page 187 , allows both reading and writing to other PostgreSQL databases (even on
remote servers with lower versions of PostgreSQL). Along with this change is an
upgrade of the FDW API to implement writable functionality.
• Numerous improvements were made to replication. Most notably, replication is
now architecture-independent and supports streaming-only remastering.
• Using C, you can write user-defined background workers for automating database
tasks.
• You can use triggers on data-definition events.
• A new watch psql command is available. See “Watching Statements” on page 50 .
• You can use a new COPY DATA command both to import from and export to external
programs. We demonstrate this in “Copy from/to Program” on page 53 .
PostgreSQL 9.2: New Features
The notable features released with version 9.2 (September 2012) are:
• You can perform index-only scans. If you need to retrieve columns that are already
a part of an index, PostgreSQL skips the unnecessary trip back to the table. You'll
see significant speed improvement in key-value queries as well as aggregates that
use only key values such as COUNT(*) .
• In-memory sort operations are improved by as much as 20%.
• Improvements were made in prepared statements . A prepared statement is now
parsed, analyzed, and rewritten, but you can skip the planning to avoid being tied
down to specific argument inputs. You can also now save the plans of a prepared
statement that depend on arguments. This reduces the chance that a prepared
statement will perform worse than an equivalent ad hoc query.
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