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my_base.h:

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Add comment about what kind of key value prefixes HA_READ_KEY_PREFIX_LAST etc. allow as a search key
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heikki@hundin.mysql.fi 2003-02-18 19:57:05 +02:00
parent e690ea09f7
commit 75782a506d
1 changed files with 15 additions and 0 deletions
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include/my_base.h
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@ -49,6 +49,21 @@
/* The following is parameter to ha_rkey() how to use key */
/* We define a complete-field prefix of a key value as a prefix where the
last included field in the prefix contains the full field, not just some bytes
from the start of the field. A partial-field prefix is allowed to
contain only a few first bytes from the last included field.
Below HA_READ_KEY_EXACT, ..., HA_READ_BEFORE_KEY can take a
complete-field prefix of a key value as the search key. HA_READ_PREFIX
and HA_READ_PREFIX_LAST could also take a partial-field prefix, but
currently (4.0.10) they are only used with complete-field prefixes. MySQL uses
a padding trick to implement LIKE 'abc%' queries.
NOTE that in InnoDB HA_READ_PREFIX_LAST will NOT work with a partial-field
prefix because InnoDB currently strips spaces from the end of varchar
fields! */
enum ha_rkey_function {
HA_READ_KEY_EXACT, /* Find first record else error */
HA_READ_KEY_OR_NEXT, /* Record or next record */