Describes the lookup and candidate selection logic used to resolve a MySQL/MariaDB collation for each EDB text column.
Each text column (CHAR, VARCHAR, CLOB) is resolved using four keys:
| Key | Description |
|---|---|
| DB type | csANSI or csUnicode — the EDB session
character set |
| Family | binary for UNI/ANSI bases;
locale for named locale bases (PTG,
ENU, DEU, …) |
| Target charset | The charset selected on the Target Database tab
(e.g. utf8mb4) |
| Modifiers | Normalised EDB modifiers: '', _CI,
_AI, or _CI_AI (_KI and
_WI are dropped) |
Each map entry contains two ordered candidate lists — one for MySQL, one for MariaDB. The converter picks the first candidate that:
| Condition | When used |
|---|---|
| (empty — Always) | Unconditionally. Every entry must have at least one Always candidate as the final fallback. |
| If AI-safe | Only when mapping to an accent-insensitive collation cannot break uniqueness. |
| If CI-safe | Only when mapping to a case-insensitive collation cannot break uniqueness. |
| If AI-safe and CI-safe | Only when both conditions are met. |
AI-safe — a column is AI-safe when it does not
participate in a PRIMARY KEY or UNIQUE constraint, or when its EDB
collation already has the _AI modifier on a locale base.
Columns outside unique constraints are always AI-safe.
CI-safe — analogous: a column in a unique constraint
is CI-safe only if its EDB collation already has _CI.
If No accented characters in CHAR/VARCHAR is checked on the Source Database tab, all columns are treated as AI-safe.
Typical candidate list for a _CI entry:
1. utf8mb4_0900_ai_ci — If AI-safe and CI-safe (best: CI + AI)
2. utf8mb4_unicode_ci — If CI-safe (CI only, accent-sensitive)
3. utf8mb4_general_ci — Always (safe fallback)When no map entry exists for the key combination, or all candidates fail:
This always produces a valid script, but the column’s sort order may differ from the original EDB behaviour.
A COLLATE clause is emitted only when the resolved
collation differs from the table default.
Columns that match the table default inherit it implicitly — no explicit
COLLATE clause is added.
When a column has no explicit EDB collation (inherited at table level), EDB2MySQL uses the most frequently occurring collation in the source database as a proxy. This dominant collation is shown in the Collation Analysis panel on the Source Database tab.