## 1 Mnesia Release Notes

This document describes the changes made to the Mnesia system from version to version. The intention of this document is to list all incompatibilities as well as all enhancements and bugfixes for every release of Mnesia. Each release of Mnesia thus constitutes one section in this document. The title of each section is the version number of Mnesia.

### 1.1 Mnesia 4.4.7

#### 1.1.1 Fixed Bugs and Malfunctions

- Disallowed match patterns ('_', and '$n') as argument to mnesia:delete_object/1 and friends.
  Own Id: OTP-7524

#### 1.1.2 Improvements and New Features

- Introduced a few new functions in Mnesia: mnesia:read/2, mnesia:first/3, mnesia:last/3, mnesia:prev/4, mnesia:next/4, mnesia_frag:first/1, mnesia_frag:last/1, mnesia_frag:prev/2, mnesia_frag:next/2.
  Own Id: OTP-7625

### 1.2 Mnesia 4.4.6

#### 1.2.1 Fixed Bugs and Malfunctions

- mnesia:restore/2 aborted if a EXIT message appeared in the client message queue.
  Own Id: OTP-7585 Aux Id: seq11046

### 1.3 Mnesia 4.4.5

#### 1.3.1 Improvements and New Features

- mnesia:clear_table/1 does not require that all replicas of the table are available anymore.
  Own Id: OTP-7466 Aux Id: seq11015

### 1.4 Mnesia 4.4.4

#### 1.4.1 Fixed Bugs and Malfunctions

- Mnesia did not garbage collect transaction decisions on disk based nodes if no transactions where made on the local node.
  Own Id: OTP-7419

### 1.5 Mnesia 4.4.3

#### 1.5.1 Fixed Bugs and Malfunctions

- Table referred to by foreign key did not have node_pool properly cleaned up when a node was removed from the schema. Thanks Paul Mineiro.
  Own Id: OTP-7340
- Mnesia crashed and generated a core dump if a schema_transaction was running when mnesia stopped.
  Own Id: OTP-7378 Aux Id: seq10964

#### 1.5.2 Improvements and New Features

- It is now possible to delete a db node even when other disk resident nodes are down. Thanks Paul Mineiro.
  Own Id: OTP-7383

### 1.6 Mnesia 4.4.2

#### 1.6.1 Fixed Bugs and Malfunctions

- Sticky locks could lead to hanging transactions.
  Own Id: OTP-7205 Aux Id: seq10793
- mnesia:snmp_get_next_index/2 didn't work with partial index keys. Argument checking is now done according to documentation, in functions mnesia:snmp_get_row/2, mnesia:snmp_get_mnesia_key/2 and mnesia:snmp_get_next_index/2. These functions now require that RowIndex is a list.
  *** POTENTIAL INCOMPATIBILITY ***
  Own Id: OTP-7208

### 1.7 Mnesia 4.4.1

#### 1.7.1 Fixed Bugs and Malfunctions

- Snmp index tables was not initialized correctly in mnesia-4.4.
  Own Id: OTP-7170 Aux Id: seq10870

#### 1.7.2 Known Bugs and Problems

- Rearranging fragmented tables is an O(N^2) operation.
  Own Id: OTP-6300

### 1.8 Mnesia 4.4

#### 1.8.1 Fixed Bugs and Malfunctions

- Mnesia ignored the module argument to mnesia:restore/2. Thanks Paul Minerio.
  Own Id: OTP-6981

#### 1.8.2 Improvements and New Features

- Mnesia's snmp operations snmp_get_row/2, snmp_get_next_index/2 and snmp_get_mnesia_key/2 have been made context aware, i.e. inside a transaction they will compensate for table updates made in earlier in the same transaction. This might cause a performance drop if a lot of updates have been made before the invocation of these functions.
  *** POTENTIAL INCOMPATIBILITY ***
  Own Id: OTP-6856 Aux Id: seq10671
- Introduced erlang:phash/2 as new default for fragmented tables. Already existing tables will continue to use whatever hash function they where using.
  Own Id: OTP-6923
- Introduced mnesia:is_transaction/0.
  Own Id: OTP-6995 Aux Id: seq10812

#### 1.8.3 Known Bugs and Problems

- Rearranging fragmented tables is an O(N^2) operation.
  Own Id: OTP-6300

### 1.9 Previous Notes

For information about older versions see release notes history.

mnesia 4.4.7
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