MDB_node Struct Reference
[LMDB Internals]

Data Fields
unsigned short	mn_flags
unsigned short	mn_ksize
char	mn_data [1]
unsigned short	mn_lo
unsigned short	mn_hi

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Detailed Description

Header for a single key/data pair within a page. Used in pages of type P_BRANCH and P_LEAF without P_LEAF2. We guarantee 2-byte alignment for 'MDB_node's.

mn_lo and mn_hi are used for data size on leaf nodes, and for child pgno on branch nodes. On 64 bit platforms, mn_flags is also used for pgno. (Branch nodes have no flags). Lo and hi are in host byte order in case some accesses can be optimized to 32-bit word access.

Leaf node flags describe node contents. F_BIGDATA says the node's data part is the page number of an overflow page with actual data. F_DUPDATA and F_SUBDATA can be combined giving duplicate data in a sub-page/sub-database, and named databases (just F_SUBDATA).

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Field Documentation

unsigned short MDB_node::mn_lo

part of data size or pgno

unsigned short MDB_node::mn_hi

part of data size or pgno

unsigned short MDB_node::mn_flags

Node Flags

unsigned short MDB_node::mn_ksize

key size

char MDB_node::mn_data[1]

key and data are appended here

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

• mdb.c