feat(persistence): extend SqlWriter with onConflictText

src/main/kotlin/kestrel/persistence/SqlWriter.kt

@@ -234,19 +234,77 @@ object SqlWriter {
 
     fun dump(catalog: Catalog): String {
         val builder = StringBuilder()
+        // Sequences are dumped FIRST, strictly before every table - a table's own column DEFAULT
+        // can read `NEXTVAL('seq')` (see kestrel.engine.Executor.executeCreateTable's eager
+        // `catalog.sequence(...)` existence check), so replaying that CREATE TABLE on reload would
+        // fail with "no such sequence" if the sequence it names did not already exist yet.
+        for (definition in catalog.sequenceDefinitions()) {
+            builder.append("${sequenceDumpText(catalog.sequence(definition.name))}\n")
+        }
         for (tableName in catalog.tableNames) {
             val table = catalog.table(tableName)
+            // A TEMP/TEMPORARY table (see kestrel.catalog.TableSchema.temporary) is session-scoped by
+            // definition - dumping it (or its rows below) into a checkpoint would make it survive a
+            // reload, which is exactly what "temporary" promises it never does.
+            if (table.schema.temporary) continue
             builder.append("CREATE TABLE ${table.schema.name} (")
-            builder.append(table.schema.columns.joinToString(", ") { columnDefinition(it) })
+            builder.append(
+                createTableBodyText(
+                    table.schema.columns,
+                    table.schema.foreignKeys,
+                    table.schema.checks,
+                    table.schema.uniqueConstraints,
+                    table.schema.compositePrimaryKey
+                )
+            )
             builder.append(");\n")
             for (row in table.rows) {
                 builder.append("INSERT INTO ${table.schema.name} VALUES (")
-                builder.append(row.values.joinToString(", ") { literal(it) })
+                // A GENERATED column's position is dumped as the literal `DEFAULT` keyword rather
+                // than its already-computed value - the executor rejects an explicit value for a
+                // GENERATED column outright (see Executor.rejectGeneratedAssignment), and `DEFAULT`
+                // here triggers the exact same fresh-recompute path an omitted column would, which
+                // reproduces the same value on replay since the expression is a pure function of
+                // this row's other (literal, already-dumped) columns.
+                builder.append(
+                    row.values.mapIndexed { index, value ->
+                        if (table.schema.columns[index].generated != null) "DEFAULT" else literal(value)
+                    }.joinToString(", ")
+                )
                 builder.append(");\n")
             }
         }
         for (definition in catalog.indexDefinitions()) {
-            builder.append("CREATE INDEX ${definition.name} ON ${definition.tableName} (${definition.columnName});\n")
+            // An index defined on a TEMP table never gets a CREATE TABLE to attach to above, so
+            // dumping it would replay as "no such table" - skip it right along with its table.
+            if (catalog.tableOrNull(definition.tableName)?.schema?.temporary == true) continue
+            builder.append(
+                "CREATE ${if (definition.unique) "UNIQUE " else ""}INDEX ${definition.name} ON " +
+                    "${definition.tableName} (${definition.columnDisplayName});\n"
+            )
+        }
+        // A VIEW whose query reads a TEMP table is NOT specially excluded here (unlike the index/
+        // trigger cases above, its dependency can be buried arbitrarily deep in a join/subquery, not
+        // one flat tableName field) - dumping it and replaying it against a reload that never
+        // recreated that TEMP table fails loudly with "no such table", the same honest failure mode
+        // this engine already accepts for e.g. a prepared statement that does not survive reopen,
+        // rather than silently materializing an empty or wrong view.
+        for (viewName in catalog.viewNames) {
+            val view = catalog.viewOrNull(viewName)!!
+            builder.append("CREATE VIEW ${view.name} AS ${queryText(view.query)};\n")
+        }
+        // Triggers are dumped LAST, strictly after every row above has already been inserted as
+        // plain data - a trigger created before its table's INSERTs would re-fire (duplicating an
+        // AFTER trigger's side effects, or re-running a BEFORE trigger's validation) the moment
+        // this very dump is replayed on reload, since replay re-executes each of these statements
+        // for real. Creating the trigger only once the table is already fully populated means
+        // those historical rows never pass through it, while every INSERT/UPDATE/DELETE a user
+        // issues after reload still does.
+        for (definition in catalog.triggerDefinitions()) {
+            // Same reasoning as the index skip above: a trigger ON a TEMP table has no table left to
+            // attach to after reload.
+            if (catalog.tableOrNull(definition.tableName)?.schema?.temporary == true) continue
+            builder.append("${triggerText(definition)}\n")
         }
         return builder.toString()
     }
@@ -254,9 +312,23 @@ object SqlWriter {
     private fun writeInsert(statement: InsertStatement): String {
         val columns = statement.columns?.let { " (${it.joinToString(", ")})" } ?: ""
         val rows = statement.rows.joinToString(", ") { row ->
-            "(" + row.joinToString(", ") { expression(it) } + ")"
+            "(" + row.joinToString(", ") { it?.let { expression(it) } ?: "DEFAULT" } + ")"
         }
-        return "INSERT INTO ${statement.tableName}$columns VALUES $rows;"
+        val onConflict = statement.onConflict?.let { " ${onConflictText(it)}" } ?: ""
+        return "INSERT INTO ${statement.tableName}$columns VALUES $rows$onConflict;"
+    }
+
+    private fun onConflictText(clause: OnConflictClause): String {
+        val target = if (clause.targetColumns.isEmpty()) "" else " (${clause.targetColumns.joinToString(", ")})"
+        val action = when (val action = clause.action) {
+            ConflictDoNothing -> "DO NOTHING"
+            is ConflictDoUpdate -> {
+                val assignments = action.assignments.joinToString(", ") { assignment(it) }
+                val where = action.where?.let { " WHERE ${expression(it)}" } ?: ""
+                "DO UPDATE SET $assignments$where"
+            }
+        }
+        return "ON CONFLICT$target $action"
     }
 
     private fun writeUpdate(statement: UpdateStatement): String {
@@ -265,28 +337,111 @@ object SqlWriter {
         return "UPDATE ${statement.tableName} SET $assignments$where;"
     }
 
+    private fun writeTruncate(statement: TruncateTableStatement): String {
+        val identity = if (statement.restartIdentity) " RESTART IDENTITY" else ""
+        return "TRUNCATE TABLE ${statement.tableNames.joinToString(", ")}$identity${dropModeText(statement.mode)};"
+    }
+
     private fun writeDelete(statement: DeleteStatement): String {
         val where = statement.where?.let { " WHERE ${expression(it)}" } ?: ""
         return "DELETE FROM ${statement.tableName}$where;"
     }
 
-    private fun assignment(assignment: Assignment): String =
-        "${assignment.columnName} = ${expression(assignment.value)}"
-
-    private fun columnDefinition(column: Column): String {
-        val constraint = when {
-            column.primaryKey -> " PRIMARY KEY"
-            column.notNull -> " NOT NULL"
-            else -> ""
-        }
-        return "${column.name} ${column.type.displayName}$constraint"
+    /**
+     * Persisted literally like every other DML statement (see [writeInsert]/[writeUpdate]): by the
+     * time this redo-log entry replays, every earlier statement - including whatever populated a
+     * table-shaped `USING` source - has already replayed too, so re-running the exact same MERGE
+     * text against the freshly rebuilt catalog reproduces the same result deterministically.
+     */
+    private fun writeMerge(statement: MergeStatement): String {
+        val targetAlias = statement.targetAlias?.let { " AS $it" } ?: ""
+        val whenClauses = statement.whenClauses.joinToString(" ") { mergeWhenClauseText(it) }
+        return "MERGE INTO ${statement.targetTable}$targetAlias USING ${fromItemText(statement.source)} " +
+            "ON ${expression(statement.onCondition)} $whenClauses;"
     }
 
+    private fun mergeWhenClauseText(clause: MergeWhenClause): String {
+        val condition = clause.condition?.let { " AND ${expression(it)}" } ?: ""
+        return when (clause) {
+            is MergeMatchedUpdate ->
+                "WHEN MATCHED$condition THEN UPDATE SET ${clause.assignments.joinToString(", ") { assignment(it) }}"
+            is MergeMatchedDelete -> "WHEN MATCHED$condition THEN DELETE"
+            is MergeNotMatchedInsert -> {
+                val columns = clause.columns?.let { " (${it.joinToString(", ")})" } ?: ""
+                val values = clause.values.joinToString(", ") { it?.let { value -> expression(value) } ?: "DEFAULT" }
+                "WHEN NOT MATCHED$condition THEN INSERT$columns VALUES ($values)"
+            }
+        }
+    }
+
+    private fun assignment(assignment: Assignment): String =
+        "${assignment.columnName} = ${assignment.value?.let { expression(it) } ?: "DEFAULT"}"
+
+    private fun columnDefinition(column: Column): String = buildString {
+        append(column.name)
+        append(" ")
+        append(column.type.displayWith(column.precision, column.scale))
+        when {
+            column.primaryKey -> append(" PRIMARY KEY")
+            column.notNull -> append(" NOT NULL")
+        }
+        if (column.collation != Collation.Binary) append(" COLLATE ${column.collation.sqlName}")
+        column.default?.let { append(" DEFAULT ${expression(it)}") }
+        column.generated?.let { append(" GENERATED ALWAYS AS (${expression(it)}) STORED") }
+    }
+
+    private fun alterTableText(statement: AlterTableStatement): String {
+        val action = when (val action = statement.action) {
+            is AddColumn -> "ADD COLUMN ${columnDefinition(action.column)}"
+            is DropColumn -> "DROP COLUMN ${action.columnName}${dropModeText(action.mode)}"
+            is RenameColumn -> "RENAME COLUMN ${action.oldName} TO ${action.newName}"
+            is RenameTable -> "RENAME TO ${action.newName}"
+            is AddConstraint -> "ADD ${addedConstraintText(action.constraint)}"
+            is DropConstraint -> "DROP CONSTRAINT ${action.name}${dropModeText(action.mode)}"
+            is ChangeColumnType -> {
+                val using = action.using?.let { " USING ${expression(it)}" } ?: ""
+                "ALTER COLUMN ${action.columnName} TYPE ${action.newType.displayWith(action.precision, action.scale)}$using"
+            }
+        }
+        return "ALTER TABLE ${statement.tableName} $action;"
+    }
+
+    private fun addedConstraintText(constraint: AddedConstraint): String = when (constraint) {
+        is AddedCheck -> constraintText(constraint.check.name, "CHECK (${expression(constraint.check.expression)})")
+        is AddedUnique -> constraintText(constraint.unique.name, "UNIQUE (${constraint.unique.columns.joinToString(", ")})")
+        is AddedForeignKey -> constraintText(constraint.foreignKey.name, foreignKeyText(constraint.foreignKey))
+    }
+
+    private fun constraintText(name: String?, body: String): String =
+        if (name != null) "CONSTRAINT $name $body" else body
+
+    private fun createTableBodyText(
+        columns: List<Column>,
+        foreignKeys: List<ForeignKeyConstraint>,
+        checks: List<CheckConstraint>,
+        uniqueConstraints: List<UniqueConstraint>,
+        compositePrimaryKey: List<String> = emptyList()
+    ): String {
+        val parts = columns.map { columnDefinition(it) } +
+            (if (compositePrimaryKey.isNotEmpty()) listOf("PRIMARY KEY (${compositePrimaryKey.joinToString(", ")})") else emptyList()) +
+            foreignKeys.map { constraintText(it.name, foreignKeyText(it)) } +
+            checks.map { constraintText(it.name, "CHECK (${expression(it.expression)})") } +
+            uniqueConstraints.map { constraintText(it.name, "UNIQUE (${it.columns.joinToString(", ")})") }
+        return parts.joinToString(", ")
+    }
+
+    private fun foreignKeyText(fk: ForeignKeyConstraint): String = buildString {
+        append("FOREIGN KEY (${fk.columns.joinToString(", ")}) REFERENCES ${fk.referencedTable} (${fk.referencedColumns.joinToString(", ")})")
+        if (fk.onDelete != ForeignKeyAction.NoAction) append(" ON DELETE ${fk.onDelete.sqlKeyword}")
+        if (fk.onUpdate != ForeignKeyAction.NoAction) append(" ON UPDATE ${fk.onUpdate.sqlKeyword}")
+    }
+
+    private fun dropModeText(mode: DropMode): String = if (mode == DropMode.Cascade) " CASCADE" else ""
+
     private fun expression(expression: Expression): String = when (expression) {
         is LiteralExpression -> literal(expression.value)
         is ColumnExpression -> expression.qualifier?.let { "$it.${expression.name}" } ?: expression.name
-        is FunctionExpression ->
-            "${expression.name}(${if (expression.star) "*" else expression.argument?.let { expression(it) } ?: ""})"
+        is FunctionExpression -> "${expression.name}(${functionArgumentsText(expression)})${filterClauseText(expression)}"
         is BinaryExpression ->
             "(${expression(expression.left)} ${expression.operator.symbol} ${expression(expression.right)})"
         is UnaryExpression -> "(${expression.operator.symbol} ${expression(expression.operand)})"