feat(sql): add addColumn and changeColumnType to DiskCatalog
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dualfroz committed
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commit
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1 file changed
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@@ -491,3 +491,164 @@ class DiskCatalog private constructor(
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}
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}
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}
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}
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/**
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* Appends a new column (already validated by [DiskExecutor]) to every existing row - mirrors
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* [kestrel.catalog.Catalog.addColumn]. [valueForRow] backfills every pre-existing row (each
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* called with that row's OLD, pre-append values, then [DiskTable.rewriteRows]-transformed to
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* carry the result) - a constant lambda for a plain DEFAULT, or a fresh per-row expression
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* evaluation for GENERATED ALWAYS AS; a table with zero rows just gets the new schema with
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* nothing to rewrite.
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*/
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fun addColumn(tableName: String, column: Column, valueForRow: (Row) -> Value) {
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val row = rowOrThrow(tableName)
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val schema = row.table.schema
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if (schema.columnIndex(column.name) != null) {
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throw DiskCatalogException("duplicate column name: ${column.name}")
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}
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val newSchema = TableSchema(
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schema.name, schema.columns + column, schema.foreignKeys, schema.checks, schema.uniqueConstraints, schema.compositePrimaryKey
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)
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val txn = engine.beginTransaction()
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try {
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row.table.rewriteRows(txn, newSchema) { existingRow -> Row(existingRow.values + valueForRow(existingRow)) }
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persistEntry(tableName.lowercase(), txn)
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engine.commit(txn)
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} catch (failure: Exception) {
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engine.abort(txn)
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throw failure
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}
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}
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/**
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* `ALTER TABLE t ALTER COLUMN col TYPE ...` - mirrors [kestrel.catalog.Catalog.changeColumnType],
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* built on [DiskTable.rewriteRows] exactly like [addColumn] rather than [addColumn]'s own
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* `List<Value> -> Value` append shape, since this replaces an EXISTING position instead of
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* appending a new one. Unlike the in-memory engine's [kestrel.engine.Executor], which validates
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* every row up front and only ever calls its own `Catalog.changeColumnType` once every row is
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* already known-good, [valueForRow] here is BOTH the value-computation AND the NOT NULL/CHECK
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* validation step (see [DiskExecutor.executeChangeColumnType]) - a failure partway through
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* throws out of [DiskTable.rewriteRows]'s loop, and the `catch` below aborts the transaction,
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* unwinding every row already rewritten. Same "validate lazily, rely on abort to undo a partial
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* per-row rewrite" contract [addColumn] already leans on for a NOT NULL `GENERATED ALWAYS AS`
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* backfill.
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*/
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fun changeColumnType(tableName: String, columnName: String, newColumn: Column, valueForRow: (Row) -> Value) {
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val row = rowOrThrow(tableName)
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val schema = row.table.schema
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val columnIndex = schema.columnIndex(columnName)
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?: throw DiskCatalogException("no such column: $columnName in table $tableName")
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val newColumns = schema.columns.toMutableList().also { it[columnIndex] = newColumn }
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val newSchema = TableSchema(
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schema.name, newColumns, schema.foreignKeys, schema.checks, schema.uniqueConstraints, schema.compositePrimaryKey
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)
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val txn = engine.beginTransaction()
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try {
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row.table.rewriteRows(txn, newSchema) { existingRow ->
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val values = existingRow.values.toMutableList()
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values[columnIndex] = valueForRow(existingRow)
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Row(values)
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}
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persistEntry(tableName.lowercase(), txn)
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engine.commit(txn)
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} catch (failure: Exception) {
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engine.abort(txn)
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throw failure
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}
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}
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/**
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* RESTRICT (default) rejects the drop if [columnName] is used by another table's FOREIGN KEY,
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* this table's own FOREIGN KEY, a UNIQUE constraint, a CHECK constraint, or a secondary index -
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* CASCADE removes all of those alongside the column itself. Mirrors
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* [kestrel.catalog.Catalog.dropColumn], including that a PRIMARY KEY column can never be
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* dropped, with or without CASCADE.
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*/
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fun dropColumn(tableName: String, columnName: String, cascade: Boolean) {
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val key = tableName.lowercase()
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val row = rowOrThrow(tableName)
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val schema = row.table.schema
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schema.columnIndex(columnName) ?: throw DiskCatalogException("no such column: $columnName in table $tableName")
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if (schema.columns.size == 1) {
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throw DiskCatalogException("cannot drop $columnName: table $tableName would be left with no columns")
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}
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if (schema.primaryKeyColumns.any { it.equals(columnName, ignoreCase = true) }) {
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throw DiskCatalogException("cannot drop column $columnName because it is part of the PRIMARY KEY of $tableName")
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}
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// Mirrors kestrel.catalog.Catalog.dropColumn: a GENERATED column can only ever read this
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// table's own non-GENERATED columns, so dropping columnName orphans any GENERATED column
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// depending on it exactly like a CHECK constraint referencing it - CASCADE drops it too,
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// RESTRICT blocks the whole drop instead. GENERATED can never be a PRIMARY KEY column, so
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// there is no "cascaded into dropping the PRIMARY KEY" case to guard against here.
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val ownGeneratedDependents = schema.columns.filter { column ->
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!column.name.equals(columnName, ignoreCase = true) &&
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column.generated?.let { CheckExpressionColumns.references(it, columnName) } == true
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}
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val droppedNames = (ownGeneratedDependents.map { it.name } + columnName).map { it.lowercase() }.toSet()
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val droppedIndices = schema.columns.withIndex()
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.filter { (_, column) -> column.name.lowercase() in droppedNames }
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.map { it.index }
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.toSet()
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val referencingForeignKeys = rowsByName.entries.filter { (otherKey, other) ->
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otherKey != key && other.table.schema.foreignKeys.any { fk ->
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fk.referencedTable.equals(tableName, ignoreCase = true) && fk.referencedColumns.any { it.lowercase() in droppedNames }
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}
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}
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val ownForeignKeys = schema.foreignKeys.filter { fk -> fk.columns.any { it.lowercase() in droppedNames } }
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val ownUniqueConstraints = schema.uniqueConstraints.filter { unique -> unique.columns.any { it.lowercase() in droppedNames } }
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val ownChecks = schema.checks.filter { check -> droppedNames.any { name -> CheckExpressionColumns.references(check.expression, name) } }
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val dependentIndexes = row.table.secondaryIndexes.filter { it.columnNames.any { c -> c.lowercase() in droppedNames } }
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if (!cascade) {
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val reasons = mutableListOf<String>()
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if (ownGeneratedDependents.isNotEmpty()) {
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reasons.add(
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"column(s) ${ownGeneratedDependents.joinToString(", ") { it.name }} are GENERATED columns that depend on it"
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)
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}
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if (referencingForeignKeys.isNotEmpty()) {
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reasons.add(
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"table(s) ${referencingForeignKeys.joinToString(", ") { it.value.table.schema.name }} have a FOREIGN KEY referencing it"
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)
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}
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if (ownForeignKeys.isNotEmpty()) reasons.add("it is used by one of its own FOREIGN KEY constraints")
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if (ownUniqueConstraints.isNotEmpty()) reasons.add("it is used by a UNIQUE constraint")
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if (ownChecks.isNotEmpty()) reasons.add("it is used by a CHECK constraint")
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if (dependentIndexes.isNotEmpty()) {
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reasons.add("index(es) ${dependentIndexes.joinToString(", ") { it.name }} are defined on it")
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}
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if (reasons.isNotEmpty()) {
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throw DiskCatalogException(
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"cannot drop column $columnName from $tableName because ${reasons.joinToString("; ")}; use CASCADE"
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)
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}
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}
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val newColumns = schema.columns.filterNot { it.name.lowercase() in droppedNames }
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val newForeignKeys = schema.foreignKeys - ownForeignKeys.toSet()
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val newUniqueConstraints = schema.uniqueConstraints - ownUniqueConstraints.toSet()
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val newChecks = schema.checks - ownChecks.toSet()
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val newSchema = TableSchema(schema.name, newColumns, newForeignKeys, newChecks, newUniqueConstraints, schema.compositePrimaryKey)
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val txn = engine.beginTransaction()
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try {
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for (indexName in dependentIndexes.map { it.name }) row.table.dropSecondaryIndexByName(indexName, txn)
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row.table.rewriteRows(txn, newSchema) { existingRow ->
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Row(existingRow.values.filterIndexed { valueIndex, _ -> valueIndex !in droppedIndices })
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}
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persistEntry(key, txn)
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for ((otherKey, other) in referencingForeignKeys) {
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val updatedForeignKeys = other.table.schema.foreignKeys.filterNot { fk ->
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fk.referencedTable.equals(tableName, ignoreCase = true) && fk.referencedColumns.any { it.lowercase() in droppedNames }
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}
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other.table.replaceSchemaMetadata(withForeignKeys(other.table.schema, updatedForeignKeys))
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persistEntry(otherKey, txn)
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}
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engine.commit(txn)
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} catch (failure: Exception) {
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engine.abort(txn)
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throw failure
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}
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}
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