提交 ef110c0a 编写于 作者: B Bruce Momjian

Update HISTORY

上级 658b58dc
......@@ -46,7 +46,7 @@
Function-inlining for simple SQL functions
Simple SQL functions can now be inlined by including their SQL
in the main query. This improves performance by eliminating
per-call overhead. That means, simple SQL functions now behave
per-call overhead. That means simple SQL functions now behave
like macros.
Full support for IPv6 connections and IPv6 address data types
......@@ -58,11 +58,11 @@
Several people very familiar with the SSL API have overhauled
our SSL code to improve SSL key negotiation and error recovery.
Make free space map to efficiently reuse empty index pages, and other
Make free space map efficiently reuse empty index pages, and other
free space management improvements
In previous releases, B-tree index pages that were left empty
because of deleted rows could only be reused by rows with index
values similar to the original rows indexed on that page. In
values similar to the rows originally indexed on that page. In
7.4, "VACUUM" records empty index pages and allows them to be
reused for any future index rows.
......@@ -71,12 +71,12 @@
to access information about the schema objects defined in a
database.
Cursors conform more closely with the SQL standard
Cursors conform more closely to the SQL standard
The commands "FETCH" and "MOVE" have been overhauled to conform
more closely to the SQL standard.
Cursors can exist outside transactions
These cursors are also called holdable cursors
These cursors are also called holdable cursors.
New client-to-server protocol
The new protocol adds error codes, more status information,
......@@ -124,7 +124,7 @@
Significant effort was invested to make the messages more
consistent and user-oriented. If your applications try to detect
different error conditions by parsing the error message, you are
strongly encourage to use the new error code facility.
strongly encouraged to use the new error code facility instead.
* Inner joins using the explicit JOIN syntax may behave differently
because they are now better optimized.
* A number of server configuration parameters have been renamed for
......@@ -238,8 +238,8 @@ Performance Improvements
of function-allocated memory when the function call completes,
reducing the total memory used by functions.
* Improve GEQO optimizer performance (Tom)
There were several inefficiencies in the way the GEQO optimizer
managed potential query paths. This release fixes this.
This release fixes several inefficiencies in the way the GEQO
optimizer manages potential query paths.
* Allow IN/NOT IN to be handled via hash tables (Tom)
* Improve NOT IN (subquery) performance (Tom)
* Allow most IN subqueries to be processed as joins (Tom)
......@@ -430,8 +430,9 @@ Utility Command Changes
deleted on transaction commit.
* Allow cursors outside transactions using WITH HOLD (Neil)
In previous releases, cursors were removed at the end of the
transaction. Using WITH HOLD, the current release allows cursors
to remain readable after the creating transaction.
transaction that created them. Cursors can now be created with the
WITH HOLD option, which allows them to continue to be accessed
after the creating transaction has committed.
* FETCH 0 and MOVE 0 now do nothing (Bruce)
In previous releases, FETCH 0 fetched all remaining rows, and MOVE
0 moved to the end of the cursor.
......@@ -441,10 +442,12 @@ Utility Command Changes
In prior releases, the row count returned by "FETCH" and "MOVE"
did not accurately reflect the number of rows processed.
* Properly handle SCROLL with cursors, or report an error (Neil)
Certain cursors can not be fetched backwards optimally. By
specifying SCROLL, extra work will be performed to guarantee that
the cursor can be fetched in reverse or random order.
* Implement SQL-compatible option FIRST, LAST, ABSOLUTE n, RELATIVE
Allowing random access (both forward and backward scrolling) to
some kinds of queries cannot be done without some additional work.
If SCROLL is specified when the cursor is created, this additional
work will be performed. Furthermore, if the cursor has been
created with NO SCROLL, no random access is allowed.
* Implement SQL-compatible options FIRST, LAST, ABSOLUTE n, RELATIVE
n for "FETCH" and "MOVE" (Tom)
* Allow "EXPLAIN" on "DECLARE CURSOR" (Tom)
* Allow "CLUSTER" to use index marked as pre-clustered by default
......@@ -460,8 +463,9 @@ Utility Command Changes
* Recover from "COPY" failure cleanly (Tom)
* Prevent possible memory leaks in "COPY" (Tom)
* Make "TRUNCATE" transaction-safe (Rod)
"TRUNCATE" can now be used inside a transaction, and rolled back
if the transaction aborts.
"TRUNCATE" can now be used inside a transaction. If the
transaction aborts, the changes made by the "TRUNCATE" are
automatically rolled back.
* Allow prepare/bind of utility commands like "FETCH" and "EXPLAIN"
(Tom)
* Add "EXPLAIN EXECUTE" (Neil)
......@@ -758,8 +762,8 @@ Contrib Changes
* Fix bug in metaphone() in fuzzystrmatch
* Improve adddepend (Rod)
* Update spi/timetravel (Böjthe Zoltán)
* Fix dbase "-s" option and improve non-ASCII handling (Thomas
Behr, Márcio Smiderle)
* Fix dbase "-s" option and improve non-ASCII handling (Thomas Behr,
Márcio Smiderle)
* Remove array module because features now included by default (Joe)
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