72 lines
2.2 KiB
Plaintext
72 lines
2.2 KiB
Plaintext
m4_comment([$Id: db_key_range.so,v 10.24 2007/10/24 16:06:06 bostic Exp $])
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define(M4PAGELOCAL, dbh_key_range)
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include(m4/m4.seealso)
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m4_pf_header(m4_ref(dbh_key_range),
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ifelse(M4API, C_API, [dnl
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int
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DB-__GT__key_range(DB *db, DB_TXN *txnid,
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DBT *key, DB_KEY_RANGE *key_range, u_int32_t flags);
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])
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ifelse(M4API, CXX_API, [dnl
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int
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Db::key_range(DbTxn *txnid
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Dbt *key, DB_KEY_RANGE *key_range, u_int32_t flags);
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]))
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m4_p([dnl
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The m4_refT(dbh_key_range) returns an estimate of the proportion of keys
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that are less than, equal to, and greater than the specified key. The
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underlying database must be of type Btree.])
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m4_p([dnl
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The m4_refT(dbh_key_range) fills in a structure of type DB_KEY_RANGE. The
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following data fields are available from the DB_KEY_RANGE structure:])
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m4_tagbegin
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m4_field(double, less,
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[A value between 0 and 1, the proportion of keys less than the specified
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key.])
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m4_field(double, equal,
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[A value between 0 and 1, the proportion of keys equal to the specified
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key.])
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m4_field(double, greater,
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[A value between 0 and 1, the proportion of keys greater than the
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specified key.])
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m4_tagend
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m4_p([dnl
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Values are in the range of 0 to 1; for example, if the field
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m4_arg(less) is 0.05, 5% of the keys in the database are less than the
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m4_arg(key) parameter. The value for m4_arg(equal) will be zero if
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there is no matching key, and will be non-zero otherwise.])
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m4_return(dbh_key_range, std)
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m4_parambegin
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m4_param_key
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m4_param(key_range, [dnl
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The estimates are returned in the m4_arg(key_range) parameter, which
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contains three elements of type double: m4_arg(less), m4_arg(equal), and
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m4_arg(greater). Values are in the range of 0 to 1; for example, if the
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field m4_arg(less) is 0.05, 5% of the keys in the database are less than
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the m4_arg(key) parameter. The value for m4_arg(equal) will be zero if
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there is no matching key, and will be non-zero otherwise.])
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m4_param_txn(dbh_key_range,, [dnl
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The m4_refT(dbh_key_range) does not retain the locks it acquires for the
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life of the transaction, so estimates may not be repeatable.])
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m4_unusedflags
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m4_paramend
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m4_err(dbh_key_range, deadlock, rephandle, replockout,
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einval, [the underlying database was not of type Btree])
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m4_seealso(Db)
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m4_page_footer
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