Import BSDDB 4.7.25 (as of svn r89086)
This commit is contained in:
Zachary Ware
123
docs_src/db/db_compact.so
Normal file
123
docs_src/db/db_compact.so
Normal file
@@ -0,0 +1,123 @@
|
||||
m4_comment([$Id: db_compact.so,v 1.8 2008/04/30 15:25:34 mbrey Exp $])
|
||||
|
||||
define(M4PAGELOCAL, dbh_compact)
|
||||
include(m4/m4.seealso)
|
||||
|
||||
m4_pf_header(m4_ref(dbh_compact),
|
||||
ifelse(M4API, C_API, [dnl
|
||||
int
|
||||
DB-__GT__compact(DB *db, DB_TXN *txnid,
|
||||
DBT *start, DBT *stop, DB_COMPACT *c_data, u_int32_t flags, DBT *end);
|
||||
])
|
||||
ifelse(M4API, CXX_API, [dnl
|
||||
int
|
||||
Db::compact(DbTxn *txnid,
|
||||
Dbt *start, Dbt *stop, DB_COMPACT *c_data, u_int32_t flags, Dbt *end);
|
||||
]))
|
||||
|
||||
m4_p([dnl
|
||||
The m4_refT(dbh_compact) compacts Btree and Recno access method
|
||||
databases, and optionally returns unused Btree, Hash or Recno database
|
||||
pages to the underlying filesystem.])
|
||||
|
||||
m4_return(dbh_compact, std)
|
||||
|
||||
m4_parambegin
|
||||
|
||||
m4_param(txnid, [dnl
|
||||
If the operation is part of an application-specified transaction, the
|
||||
m4_arg(txnid) parameter is a transaction handle returned from
|
||||
m4_ref(txn_begin); otherwise NULL. If no transaction handle is
|
||||
specified, but the operation occurs in a transactional database, the
|
||||
operation will be implicitly transaction protected using multiple
|
||||
transactions. These transactions will be periodically committed to
|
||||
avoid locking large sections of the tree. Any deadlocks encountered
|
||||
cause the compaction operation to retried from the point of the last
|
||||
transaction commit.])
|
||||
|
||||
m4_param(start, [dnl
|
||||
If non-NULL, the m4_arg(start) parameter is the starting point for
|
||||
compaction in a Btree or Recno database. Compaction will start at the
|
||||
smallest key greater than or equal to the specified key. If NULL,
|
||||
compaction will start at the beginning of the database.])
|
||||
|
||||
m4_param(stop, [dnl
|
||||
If non-NULL, the m4_arg(stop) parameter is the stopping point for
|
||||
compaction in a Btree or Recno database. Compaction will stop at the
|
||||
page with the smallest key greater than the specified key. If NULL,
|
||||
compaction will stop at the end of the database.])
|
||||
|
||||
m4_param(c_data, [m4_p([dnl
|
||||
If non-NULL, the m4_arg(c_data) parameter contains additional compaction
|
||||
configuration parameters, and returns compaction operation statistics,
|
||||
in a structure of type DB_COMPACT.])
|
||||
m4_p([dnl
|
||||
The following input configuration fields are available from the
|
||||
DB_COMPACT structure:])
|
||||
m4_tagbegin
|
||||
m4_field(int, compact_fillpercent, [dnl
|
||||
If non-zero, the goal for filling pages, specified as a percentage
|
||||
between 1 and 100. Any page in a Btree or Recno databases not at or
|
||||
above this percentage full will be considered for compaction. The
|
||||
default behavior is to consider every page for compaction, regardless
|
||||
of its page fill percentage.])
|
||||
m4_field(int, compact_pages, [dnl
|
||||
If non-zero, the call will return after that number of pages have been
|
||||
freed.])
|
||||
m4_field(db_timeout_t, compact_timeout, [dnl
|
||||
If non-zero, and no m4_arg(txnid) parameter was specified, the lock
|
||||
timeout set for implicit transactions, in microseconds.])
|
||||
m4_tagend
|
||||
m4_p([dnl
|
||||
The following output statistics fields are available from the
|
||||
DB_COMPACT structure:])
|
||||
m4_tagbegin
|
||||
m4_field(u_int32_t, compact_deadlock, [dnl
|
||||
An output statistics parameter: if no m4_arg(txnid) parameter was
|
||||
specified, the number of deadlocks which occurred.])
|
||||
m4_field(u_int32_t, compact_pages_examine, [dnl
|
||||
An output statistics parameter: the number of database pages reviewed
|
||||
during the compaction phase.])
|
||||
m4_field(u_int32_t, compact_pages_free, [dnl
|
||||
An output statistics parameter: the number of database pages freed during
|
||||
the compaction phase.])
|
||||
m4_field(u_int32_t, compact_levels, [dnl
|
||||
An output statistics parameter: the number of levels removed from the
|
||||
Btree or Recno database during the compaction phase.])
|
||||
m4_field(u_int32_t, compact_pages_truncated, [dnl
|
||||
An output statistics parameter: the number of database pages returned
|
||||
to the filesystem.])
|
||||
m4_tagend])
|
||||
|
||||
m4_param(flags, [dnl
|
||||
m4_sf_zmust
|
||||
m4_tagbegin
|
||||
m4_tag(m4_idef(DB_FREELIST_ONLY), [dnl
|
||||
Do no page compaction, only returning pages to the filesystem that are
|
||||
already free and at the end of the file. This flag must be set if the
|
||||
database is a Hash access method database.])
|
||||
m4_tag(m4_idef(DB_FREE_SPACE), [dnl
|
||||
Return pages to the filesystem when possible.
|
||||
If this flag is not specified, pages emptied as a result of compaction
|
||||
will be placed on the free list for re-use, but never returned to the
|
||||
filesystem.
|
||||
m4_p([dnl
|
||||
Note that only pages at the end of a file can be returned to the
|
||||
filesystem. Because of the one-pass nature of the compaction algorithm,
|
||||
any not emptied page near the end of the file inhibits returning pages to
|
||||
the file system. A repeated call to the m4_refT(dbh_compact) with a low
|
||||
m4_arg(compact_fillpercent) may be used to return pages in this case.])])
|
||||
m4_tagend])
|
||||
|
||||
m4_param(end, [dnl
|
||||
If non-NULL, the m4_arg(end) parameter will be filled in with the
|
||||
database key marking the end of the compaction operation in a Btree or
|
||||
Recno database. This is generally the first key of the page where the
|
||||
operation stopped.])
|
||||
|
||||
m4_paramend
|
||||
|
||||
m4_err(dbh_compact, deadlock, rephandle, replockout, readonly, einval,,)
|
||||
|
||||
m4_seealso(Db)
|
||||
m4_page_footer
|
||||
Reference in New Issue
Block a user