Add support for concurrent index creation statements (#148)

PG supports a `CONCURRENTLY` keyword on index creation that changes how the indexing proceeds under the hood. It caused a parse error before, now it doesn't!

See https://www.postgresql.org/docs/current/sql-createindex.html

src/syntax/ast.ts

@@ -410,6 +410,7 @@ export interface CreateIndexStatement extends PGNode {
     where?: Expr;
     unique?: true;
     ifNotExists?: true;
+    concurrently?: true;
     indexName?: Name;
     tablespace?: string;
     with?: CreateIndexWith[];

src/syntax/create-index.ne

@@ -10,6 +10,7 @@ createindex_statement
     -> %kw_create
         %kw_unique:?
         kw_index
+        %kw_concurrently:?
         kw_ifnotexists:?
         word:?
         %kw_on
@@ -24,14 +25,15 @@ createindex_statement
          {% x => track(x, {
             type: 'create index',
             ...x[1] && { unique: true },
-            ...x[3] && { ifNotExists: true },
-            ...x[4] && { indexName: asName(x[4]) },
-            table: x[6],
-            ...x[7] && { using: asName(x[7]) },
-            expressions: x[9],
-            ...x[11] && { with: x[11] },
-            ...x[12] && { tablespace: unwrap(x[12]) },
-            ...x[13] && { where: unwrap(x[13]) },
+            ...x[3] && { concurrently: true },
+            ...x[4] && { ifNotExists: true },
+            ...x[5] && { indexName: asName(x[5]) },
+            table: x[7],
+            ...x[8] && { using: asName(x[8]) },
+            expressions: x[10],
+            ...x[12] && { with: x[12] },
+            ...x[13] && { tablespace: unwrap(x[13]) },
+            ...x[14] && { where: unwrap(x[14]) },
         }) %}
 
 createindex_expressions -> createindex_expression (comma createindex_expression {% last %}):* {% ([head, tail]) => {

src/syntax/create-index.spec.ts

@@ -215,4 +215,31 @@ describe('Create index', () => {
         }],
         tablespace: 'abc',
     });
+
+    checkCreateIndex(['create index concurrently blah on test(col)'], {
+        type: 'create index',
+        indexName: { name: 'blah' },
+        table: { name: 'test' },
+        concurrently: true,
+        expressions: [{
+            expression: { type: 'ref', name: 'col' },
+        }],
+    });
+    checkCreateIndex(['create index concurrently on test(col)'], {
+        type: 'create index',
+        table: { name: 'test', },
+        concurrently: true,
+        expressions: [{
+            expression: { type: 'ref', name: 'col' },
+        }],
+    });
+    checkCreateIndex(['create unique index concurrently on test(col)'], {
+        type: 'create index',
+        table: { name: 'test', },
+        concurrently: true,
+        unique: true,
+        expressions: [{
+            expression: { type: 'ref', name: 'col' },
+        }],
+    });
 });

src/to-sql.ts

@@ -880,6 +880,9 @@ const visitor = astVisitor<IAstFullVisitor>(m => ({
 
     createIndex: c => {
         ret.push(c.unique ? 'CREATE UNIQUE INDEX ' : 'CREATE INDEX ');
+        if (c.concurrently) {
+            ret.push('CONCURRENTLY ');
+        }
         if (c.ifNotExists) {
             ret.push(' IF NOT EXISTS ');
         }