Package dev.frostlake.executor

Class KeyCollations

java.lang.Object

dev.frostlake.executor.KeyCollations

public final class KeyCollations
extends Object

The collation a sorting, grouping or de-duplicating key compares under. A collation reaches a key one of two ways — a column declared with one, or a COLLATE written into the key — so a query touching neither can skip resolving key collations altogether.

Method Summary

Modifier and Type	Method	Description
static boolean	reachable(List<String> keys, Table table, Map<String,Table> aliasToTable, List<Table> allTables)	Whether any key here could carry a collation at all: some relation in scope declares one on a column, or some key writes COLLATE itself.
static CollationSpec[]	resolve(List<String> keys, ExpressionEvaluator evaluator)	The collation each key compares under.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

reachable

public static boolean reachable(List<String> keys,
 Table table,
 Map<String,Table> aliasToTable,
 List<Table> allTables)

Whether any key here could carry a collation at all: some relation in scope declares one on a column, or some key writes COLLATE itself.

Parameters:

keys - the key expressions as written

table - the query's base relation, or null

aliasToTable - its alias map, or null

allTables - its joined relations, or null

Returns:

false when no key can be collated, and the caller can compare by code point

resolve

public static CollationSpec[] resolve(List<String> keys,
 ExpressionEvaluator evaluator)

The collation each key compares under.

Parameters:

keys - the key expressions as written

evaluator - the evaluator that resolves their columns

Returns:

one entry per key, null where the key carries no collation