bk commit - mysqldoc tree (paul:1.1580)

[paul]

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ChangeSet
  1.1580 04/05/03 15:32:37 paul@stripped +1 -0
  manual.texi:
    More on index prefix lengths.

  Docs/manual.texi
    1.1624 04/05/03 15:32:15 paul@stripped +16 -6
    More on index prefix lengths.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	paul
# Host:	kite-hub.kitebird.com
# Root:	/src/extern/MySQL/bk/mysqldoc

--- 1.1623/Docs/manual.texi	Mon May  3 15:14:26 2004
+++ 1.1624/Docs/manual.texi	Mon May  3 15:32:15 2004
@@ -52833,24 +52833,31 @@
 
 @item
 With @code{col_name(length)} syntax in an index specification, you can create
-an index that uses only the first @code{length} bytes of a @code{CHAR}
-or @code{VARCHAR} column. This can make the index file much smaller.
+an index that uses only the first @code{length} characters of a @code{CHAR}
+or @code{VARCHAR} column. Indexing only a prefix of column values like this
+can make the index file much smaller.
 @xref{Indexes}.
 
-@item
 @cindex @code{BLOB} columns, indexing
 @cindex indexes, and @code{BLOB} columns
 @cindex @code{TEXT} columns, indexing
 @cindex indexes, and @code{TEXT} columns
-Only the @code{MyISAM} and (as of MySQL 4.0.14) @code{InnoDB} table types
+The @code{MyISAM} and (as of MySQL 4.0.14) @code{InnoDB} table types also
 support indexing on @code{BLOB} and @code{TEXT} columns.  When indexing
-a @code{BLOB} or @code{TEXT} column, you @emph{must} always specify the
-length of the index, up to 255 bytes. For example:
+a @code{BLOB} or @code{TEXT} column, you @emph{must} specify a prefix
+length for the index. For example:
 
 @example
 CREATE TABLE test (blob_col BLOB, INDEX(blob_col(10)));
 @end example
 
+Prefixes can be up to 255 bytes long (or 1000 bytes for @code{MyISAM}
+and @code{InnoDB} tables as of MySQL 4.1.2).  Note that prefix limits
+are measured in bytes, whereas the prefix length in @code{CREATE TABLE}
+statements is interpreted as number of characters.  Take this into account
+when specifying a prefix length for a column that uses a multi-byte
+character set.
+
 @item
 An @code{index_col_name} specification can end with @code{ASC} or @code{DESC}.
 These keywords are allowed for future extensions for specifying ascending
@@ -79500,6 +79507,9 @@
 MySQL now supports up to 64 keys per table.
 @item
 @code{MyISAM} tables now support keys up to 1000 bytes long.
+@item
+@code{MyISAM} and @code{InnoDB} tables now support index prefix lengths up
+to 1000 bytes long.
 @item
 If you try to create a key with a key part that is too long, and it is safe
 to auto-truncate it to a smaller length, MySQL now does so.  A warning is