mirror of
https://github.com/friendica/friendica
synced 2024-11-18 07:43:51 +00:00
34 lines
1.4 KiB
Markdown
34 lines
1.4 KiB
Markdown
|
# Considerations before upgrading Friendica
|
||
|
|
|
||
|
|
* [Home](help)
|
||
|
|
|
||
|
|
## MySQL >= 5.7.4
|
||
|
|
|
||
|
|
Starting from MySQL version 5.7.4, the IGNORE keyword in ALTER TABLE statements is ignored.
|
||
|
|
This prevents automatic table deduplication if a UNIQUE index is added to a Friendica table's structure.
|
||
|
|
If a DB update fails for you while creating a UNIQUE index, make sure to manually deduplicate the table before trying the update again.
|
||
|
|
|
||
|
|
### Manual deduplication
|
||
|
|
|
||
|
|
There are two main ways of doing it, either by manually removing the duplicates or by recreating the table.
|
||
|
|
Manually removing the duplicates is usually faster if they're not too numerous.
|
||
|
|
To manually remove the duplicates, you need to know the UNIQUE index columns available in `database.sql`.
|
||
|
|
|
||
|
|
```SQL
|
||
|
|
SELECT GROUP_CONCAT(id), <index columns>, count(*) as count FROM users
|
||
|
|
GROUP BY <index columns> HAVING count >= 2;
|
||
|
|
|
||
|
|
/* delete or merge duplicate from above query */;
|
||
|
|
```
|
||
|
|
|
||
|
|
If there are too many rows to handle manually, you can create a new table with the same structure as the table with duplicates and insert the existing content with INSERT IGNORE.
|
||
|
|
To recreate the table you need to know the table structure available in `database.sql`.
|
||
|
|
|
||
|
|
```SQL
|
||
|
|
CREATE TABLE <table_name>_new <rest of the CREATE TABLE>;
|
||
|
|
INSERT IGNORE INTO <table_name>_new SELECT * FROM <table_name>;
|
||
|
|
DROP TABLE <table_name>;
|
||
|
|
RENAME TABLE <table_name>_new TO <table_name>;
|
||
|
|
```
|
||
|
|
|
||
|
|
This method is slower overall, but it is better suited for large numbers of duplicates.
|