Add support for SET TRANSACTION statements.

Author: jellelicht

src/ast-mapper.ts

@@ -87,6 +87,9 @@ export interface IAstPartialMapper {
     createSequence?(seq: a.CreateSequenceStatement): a.Statement | nil
     alterSequence?(seq: a.AlterSequenceStatement): a.Statement | nil
     begin?(begin: a.BeginStatement): a.Statement | nil
+    setTransactionSnapshot?(snapshot: a.SetTransactionSnapshot): a.Statement | nil
+    setTransaction?(transaction: a.SetTransactionMode): a.Statement | nil
+    setSession?(session: a.SetTransactionMode): a.Statement | nil
 }
 
 export type IAstFullMapper = {
@@ -247,6 +250,12 @@ export class AstDefaultMapper implements IAstMapper {
                 return this.setGlobal(val);
             case 'set timezone':
                 return this.setTimezone(val);
+            case 'set transaction snapshot':
+                return this.setTransactionSnapshot(val);
+            case 'set transaction':
+                return this.setTransaction(val);
+            case 'set session characteristics as transaction':
+                return this.setSession(val);
             case 'create sequence':
                 return this.createSequence(val);
             case 'alter sequence':
@@ -437,6 +446,17 @@ export class AstDefaultMapper implements IAstMapper {
         return val;
     }
 
+    setTransactionSnapshot?(snapshot: a.SetTransactionSnapshot): a.Statement | nil {
+        return snapshot;
+    }
+
+    setTransaction?(transaction: a.SetTransactionMode): a.Statement | nil {
+        return transaction;
+    }
+
+    setSession?(session: a.SetTransactionMode): a.Statement | nil {
+        return session;
+    }
 
     update(val: a.UpdateStatement): a.Statement | nil {
         if (!val) {

src/syntax/ast.ts

@@ -62,6 +62,18 @@ export interface BeginStatement extends PGNode {
     deferrable?: boolean;
 }
 
+export interface SetTransactionSnapshot extends PGNode {
+    type: 'set transaction snapshot';
+    snapshotId: Name;
+}
+
+export interface SetTransactionMode extends PGNode {
+    type: 'set transaction' | 'set session characteristics as transaction';
+    isolationLevel: 'serializable' | 'repeatable read' | 'read committed' | 'read uncommitted';
+    writeable?: 'read write' | 'read only';
+    deferrable?: boolean;
+}
+
 export interface DoStatement extends PGNode {
     type: 'do';
     language?: Name;

src/syntax/base.ne

@@ -144,6 +144,9 @@ kw_filter -> %word {% notReservedKw('filter')  %}
 kw_commit -> %word {% notReservedKw('commit')  %}
 kw_tablespace -> %word {% notReservedKw('tablespace')  %}
 kw_transaction -> %word {% notReservedKw('transaction')  %}
+kw_snapshot -> %word {% notReservedKw('snapshot')  %}
+kw_session -> %word {% notReservedKw('session')  %}
+kw_characteristics -> %word {% notReservedKw('characteristics')  %}
 kw_work -> %word {% notReservedKw('work')  %}
 kw_read -> %word {% notReservedKw('read')  %}
 kw_write -> %word {% notReservedKw('write')  %}

src/syntax/simple-statements.ne

@@ -34,7 +34,11 @@ simplestatements_tablespace -> kw_tablespace word {% x => track(x, {
  }) %}
 
 
-simplestatements_set -> kw_set (simplestatements_set_simple | simplestatements_set_timezone) {% last %}
+simplestatements_set -> kw_set (simplestatements_set_simple
+                              | simplestatements_set_timezone
+			      | simplestatements_set_session
+			      | simplestatements_set_transaction_snapshot
+			      | simplestatements_set_transaction) {% last %}
 
 simplestatements_set_timezone -> kw_time kw_zone simplestatements_set_timezone_val {% x => track(x, { type: 'set timezone', to: x[2] }) %}
 
@@ -65,6 +69,27 @@ simplestatements_set_val_raw
 
 simplestatements_show -> kw_show ident {% x => track(x, { type: 'show', variable: asName(x[1]) }) %}
 
+# https://www.postgresql.org/docs/current/sql-set-transaction.html
+simplestatements_set_transaction_snapshot
+    -> kw_transaction kw_snapshot ident {% x => track(x, { type: 'set transaction snapshot', snapshotId: asName(x[2]) }) %}
+
+simplestatements_set_session
+    -> kw_session kw_characteristics %kw_as kw_transaction
+                    (simplestatements_begin_isol | simplestatements_begin_writ | simplestatements_begin_def):* {%
+                    x => track(x, {
+                        type: 'set session characteristics as transaction',
+                        ...x[4].reduce((a: any, b: any) => ({...unwrap(a), ...unwrap(b)}), {}),
+                    })
+                    %}
+
+simplestatements_set_transaction
+    -> kw_transaction (simplestatements_begin_isol | simplestatements_begin_writ | simplestatements_begin_def):* {%
+                    x => track(x, {
+                        type: 'set transaction',
+                        ...x[1].reduce((a: any, b: any) => ({...unwrap(a), ...unwrap(b)}), {}),
+                    })
+                    %}
+
 
 # https://www.postgresql.org/docs/current/sql-createschema.html
 create_schema -> (%kw_create kw_schema) kw_ifnotexists:? ident {% x => track(x, {

src/syntax/simple-statements.spec.ts

@@ -247,6 +247,26 @@ describe('Simple statements', () => {
     })
 
 
+    checkStatement(`set transaction SNAPSHOT mysnapshot`, {
+        type: 'set transaction snapshot',
+        snapshotId: { name: 'mysnapshot' },
+    });
+
+    checkStatement(`set transaction isolation level repeatable read read only not deferrable`, {
+        type: 'set transaction',
+        isolationLevel:  'repeatable read',
+        writeable: 'read only',
+        deferrable: false,
+    });
+
+    checkStatement(`set session characteristics as transaction isolation level read uncommitted deferrable read write`, {
+        type: 'set session characteristics as transaction',
+        isolationLevel:  'read uncommitted',
+        writeable: 'read write',
+        deferrable: true,
+    });
+
+
     checkStatement(`select * from (select a from mytable) myalias(col_renamed)`, {
         type: 'select',
         columns: [{ expr: { type: 'ref', name: '*' } }],

src/to-sql.ts

@@ -564,6 +564,43 @@ const visitor = astVisitor<IAstFullVisitor>(m => ({
         }
     },
 
+    setTransactionSnapshot: s => {
+        ret.push('SET TRANSACTION SNAPSHOT ');
+        ret.push(name(s.snapshotId));
+    },
+
+    setTransaction: tx => {
+        ret.push('SET TRANSACTION ');
+        if (tx.isolationLevel) {
+            ret.push('ISOLATION LEVEL ', tx.isolationLevel.toUpperCase(), ' ');
+        }
+        if (tx.writeable) {
+            ret.push(tx.writeable.toUpperCase(), ' ');
+        }
+        if (typeof tx.deferrable === 'boolean') {
+            if (!tx.deferrable) {
+                ret.push('NOT ');
+            }
+            ret.push('DEFERRABLE ');
+        }
+    },
+
+    setSession: s => {
+        ret.push('SET SESSION CHARACTERISTICS AS TRANSACTION ');
+        if (s.isolationLevel) {
+            ret.push('ISOLATION LEVEL ', s.isolationLevel.toUpperCase(), ' ');
+        }
+        if (s.writeable) {
+            ret.push(s.writeable.toUpperCase(), ' ');
+        }
+        if (typeof s.deferrable === 'boolean') {
+            if (!s.deferrable) {
+                ret.push('NOT ');
+            }
+            ret.push('DEFERRABLE ');
+        }
+    },
+
     begin: beg => {
         ret.push('BEGIN ');
         if (beg.isolationLevel) {