- Support for "left join lateral" in Postgres which converts to "outer apply" in Microsoft SQL Server and Oracle.

Author: danrzeppa

lib/dialect/mssql.js

@@ -274,6 +274,16 @@ Mssql.prototype.visitFunctionCall = function(functionCall) {
   return [txt];
 };
 
+Mssql.prototype.visitJoin = function(join) {
+  if (join.subType !== 'LEFT LATERAL') return Mssql.super_.prototype.visitJoin.call(this, join);
+  var result = [];
+  this._visitingJoin = true;
+  result = result.concat(this.visit(join.from));
+  result = result.concat('OUTER APPLY');
+  result = result.concat(this.visit(join.to));
+  return result;
+};
+
 Mssql.prototype.visitOrderBy = function(orderBy) {
   var result=Mssql.super_.prototype.visitOrderBy.call(this, orderBy);
   var offsetNode=orderBy.msSQLOffsetNode;

lib/dialect/oracle.js

@@ -278,6 +278,11 @@ Oracle.prototype.visitCase = function(caseExp) {
   return Mssql.prototype.visitCase.call(this, caseExp);
 };
 
+// Using same JOIN implementation as MSSQL
+Oracle.prototype.visitJoin = function(joinExp) {
+  return Mssql.prototype.visitJoin.call(this, joinExp);
+};
+
 Oracle.prototype.visitOnConflict = function(onConflict) {
   throw new Error('Oracle does not allow onConflict clause.');
 };

lib/dialect/postgres.js

@@ -1022,6 +1022,7 @@ Postgres.prototype.visitForShare = function() {
 };
 
 Postgres.prototype.visitJoin = function(join) {
+  if (join.subType === 'LEFT LATERAL') return this.visitLeftJoinLateral(join)
   var result = [];
   this._visitingJoin = true;
   result = result.concat(this.visit(join.from));
@@ -1032,6 +1033,16 @@ Postgres.prototype.visitJoin = function(join) {
   return result;
 };
 
+Postgres.prototype.visitLeftJoinLateral = function(join) {
+  var result = [];
+  this._visitingJoin = true;
+  result = result.concat(this.visit(join.from));
+  result = result.concat('LEFT JOIN LATERAL');
+  result = result.concat(this.visit(join.to));
+  result = result.concat('ON true');
+  return result;
+};
+
 Postgres.prototype.visitLiteral = function(node) {
   var txt = [node.literal];
   if(node.alias) {

lib/node/join.js

@@ -19,5 +19,8 @@ var JoinNode = module.exports = Node.define({
   },
   leftJoin: function(other) {
     return new JoinNode('LEFT', this, other);
+  },
+  leftJoinLateral: function(other) {
+    return new JoinNode('LEFT LATERAL', this, other);
   }
 });

lib/table.js

@@ -237,6 +237,10 @@ Table.prototype.leftJoin = function(other) {
   return new JoinNode('LEFT', this.toNode(), other.toNode());
 };
 
+Table.prototype.leftJoinLateral = function(other) {
+  return new JoinNode('LEFT LATERAL', this.toNode(), other.toNode());
+};
+
 // auto-join tables based on column intropsection
 Table.prototype.joinTo = function(other) {
   return Joiner.leftJoin(this, other);

test/dialects/join-tests.js

@@ -174,3 +174,57 @@ Harness.test({
   },
   params: []
 });
+
+Harness.test({
+  query: user.select().from(user.leftJoinLateral(post.subQuery().select(post.userId))),
+  pg: {
+    text  : 'SELECT "user".* FROM "user" LEFT JOIN LATERAL (SELECT "post"."userId" FROM "post") ON true',
+    string: 'SELECT "user".* FROM "user" LEFT JOIN LATERAL (SELECT "post"."userId" FROM "post") ON true'
+  },
+  mssql: {
+    text  : 'SELECT [user].* FROM [user] OUTER APPLY (SELECT [post].[userId] FROM [post])',
+    string: 'SELECT [user].* FROM [user] OUTER APPLY (SELECT [post].[userId] FROM [post])'
+  },
+  oracle: {
+    text  : 'SELECT "user".* FROM "user" OUTER APPLY (SELECT "post"."userId" FROM "post")',
+    string: 'SELECT "user".* FROM "user" OUTER APPLY (SELECT "post"."userId" FROM "post")'
+  },
+  params: []
+});
+
+Harness.test({
+  query: user.select().from(user.leftJoinLateral(post.subQuery().select(post.userId).where(user.id.equals(post.userId)))),
+  pg: {
+    text  : 'SELECT "user".* FROM "user" LEFT JOIN LATERAL (SELECT "post"."userId" FROM "post" WHERE ("user"."id" = "post"."userId")) ON true',
+    string: 'SELECT "user".* FROM "user" LEFT JOIN LATERAL (SELECT "post"."userId" FROM "post" WHERE ("user"."id" = "post"."userId")) ON true'
+  },
+  mssql: {
+    text  : 'SELECT [user].* FROM [user] OUTER APPLY (SELECT [post].[userId] FROM [post] WHERE ([user].[id] = [post].[userId]))',
+    string: 'SELECT [user].* FROM [user] OUTER APPLY (SELECT [post].[userId] FROM [post] WHERE ([user].[id] = [post].[userId]))'
+  },
+  oracle: {
+    text  : 'SELECT "user".* FROM "user" OUTER APPLY (SELECT "post"."userId" FROM "post" WHERE ("user"."id" = "post"."userId"))',
+    string: 'SELECT "user".* FROM "user" OUTER APPLY (SELECT "post"."userId" FROM "post" WHERE ("user"."id" = "post"."userId"))'
+  },
+  params: []
+});
+
+Harness.test({
+  query: user.select().from(user
+  	.leftJoinLateral(post.subQuery().select(post.userId))
+  	.leftJoinLateral(comment.subQuery().select(comment.postId))),
+  pg: {
+    text  : 'SELECT "user".* FROM "user" LEFT JOIN LATERAL (SELECT "post"."userId" FROM "post") ON true LEFT JOIN LATERAL (SELECT "comment"."postId" FROM "comment") ON true',
+    string: 'SELECT "user".* FROM "user" LEFT JOIN LATERAL (SELECT "post"."userId" FROM "post") ON true LEFT JOIN LATERAL (SELECT "comment"."postId" FROM "comment") ON true'
+  },
+  mssql: {
+    text  : 'SELECT [user].* FROM [user] OUTER APPLY (SELECT [post].[userId] FROM [post]) OUTER APPLY (SELECT [comment].[postId] FROM [comment])',
+    string: 'SELECT [user].* FROM [user] OUTER APPLY (SELECT [post].[userId] FROM [post]) OUTER APPLY (SELECT [comment].[postId] FROM [comment])'
+  },
+  oracle: {
+    text  : 'SELECT "user".* FROM "user" OUTER APPLY (SELECT "post"."userId" FROM "post") OUTER APPLY (SELECT "comment"."postId" FROM "comment")',
+    string: 'SELECT "user".* FROM "user" OUTER APPLY (SELECT "post"."userId" FROM "post") OUTER APPLY (SELECT "comment"."postId" FROM "comment")'
+  },
+  params: []
+});
+