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MySQL 8.0.43
Source Code Documentation
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Following is a list of the terms used in the TempTable storage engine source code.
This is to avoid confusion because in the surrounding code (outside of storage/temptable) different terms are used to designate the one thing and in some cases a given term can designate different things.
For example some surrounding code reads key->records_per_key(j) where the first "key" (key->...) designates an index and the second "key" (..._key(j)) designates distinct indexed cells.
Below are the terms used in TempTable source code with some explanations.
A table consists of rows and columns.
| id | color_name | hex_code |
|---|---|---|
| 1 | Red | FF0000 |
| 2 | Orange | FF8800 |
| 3 | Yellow | FFFF00 |
| 4 | Green | 00FF00 |
| 5 | Cyan | 00FFFF |
| 6 | Blue | 0000FF |
| 7 | Pink | FF00FF |
A row is a horizontal slice from the table.
| id | color_name | hex_code |
|---|---|---|
| 1 | Red | FF0000 |
| 2 | Orange | FF8800 |
| 3 | Yellow | FFFF00 |
| 4 | Green | 00FF00 |
| 5 | Cyan | 00FFFF |
| 6 | Blue | 0000FF |
| 7 | Pink | FF00FF |
Also called "record" elsewhere.
A column is a vertical slice from the table. It has a name - "hex_code" in the example.
| id | color_name | hex_code |
|---|---|---|
| 1 | Red | FF0000 |
| 2 | Orange | FF8800 |
| 3 | Yellow | FFFF00 |
| 4 | Green | 00FF00 |
| 5 | Cyan | 00FFFF |
| 6 | Blue | 0000FF |
| 7 | Pink | FF00FF |
Also called "field" elsewhere.
A cell is where a row intersects with a column.
| id | color_name | hex_code |
|---|---|---|
| 1 | Red | FF0000 |
| 2 | Orange | FF8800 |
| 3 | Yellow | FFFF00 |
| 4 | Green | 00FF00 |
| 5 | Cyan | 00FFFF |
| 6 | Blue | 0000FF |
| 7 | Pink | FF00FF |
Also called "field" elsewhere.
An index is a complex structure covering one or more columns. Also called "key" elsewhere.
A column that is covered by an index.
An indexed cell is a cell that is covered by an index. An intersection between a row and an indexed column. Also called "key", "field", "subkey", "key part", "key segment" elsewhere.