MDB_meta Struct Reference
[LMDB Internals]

Data Fields
uint32_t	mm_magic
uint32_t	mm_version
void *	mm_address
size_t	mm_mapsize
MDB_db	mm_dbs [CORE_DBS]
pgno_t	mm_last_pg
volatile txnid_t	mm_txnid

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Detailed Description

Meta page content. A meta page is the start point for accessing a database snapshot. Pages 0-1 are meta pages. Transaction N writes meta page #(N % 2).

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Field Documentation

uint32_t MDB_meta::mm_magic

Stamp identifying this as an LMDB file. It must be set to MDB_MAGIC.

uint32_t MDB_meta::mm_version

Version number of this file. Must be set to MDB_DATA_VERSION.

void* MDB_meta::mm_address

address for fixed mapping

size_t MDB_meta::mm_mapsize

size of mmap region

MDB_db MDB_meta::mm_dbs[CORE_DBS]

first is free space, 2nd is main db

pgno_t MDB_meta::mm_last_pg

Last used page in the datafile. Actually the file may be shorter if the freeDB lists the final pages.

volatile txnid_t MDB_meta::mm_txnid

txnid that committed this page

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The documentation for this struct was generated from the following file:

• mdb.c