SysDB — System DataBase

Fixed weird behavior when collector callbacks were registered without any plugin context information (as it would, e.g., happen when using LoadPlugin instead of LoadBackend in sysdbd).

Introduced service attributes — similar to host attributes but assigned to a service object.

Don’t log “value too old” messages if an updated object uses the same timestamp as the old object.

Switched from linked-lists to AVL trees for storing all object types to reduce lookup times from O(n) to O(log n).

Added infrastructure for handling and evaluating arithmetic expressions and filters (see also the changes to the query language below).

Export various fields describing base attributes of all stored object types: last_update, age, interval, and backend. These fields may be used when querying the store.

Added support for ‘IS NULL’ attribute checks matching on non-existent attributes.

Changed ‘LOOKUP … WHERE’ queries to ‘LOOKUP … MATCHING’ to avoid confusion with SQL semantics.

Switched from ‘<obj>.name’ to ‘<obj>’ in MATCHING clauses, thus, no longer shadowing attributes called “name”.

Added support for arithmetic expressions in places that used simple data values before. Arithmetic expressions support addition, subtraction, multiplication, division, modulo, and concatenation operations. The expressions may be based on constant values or queryable fields of the stored objects (specified as ‘:last_update’, ‘:age’, ‘:interval’, and ‘:backend’).

Added ‘FILTER’ support to ‘LOOKUP’ queries. Filters are conditional expressions which may optionally be used to limit the query and the result to object (of any type) matching the filter condition.

Added support to specify date and time values.

avltree: Added an AVL tree (self-balancing binary tree) implementation.