From f3f1313d885f5dc9d6daa8afdbcecae319849fff Mon Sep 17 00:00:00 2001
From: Jesse Seldess <jesse@cockroachlabs.com>
Date: Wed, 23 Aug 2017 22:12:13 -0400
Subject: [PATCH] Add known limitation around dropping interleaved indexes

---
 v1.0/known-limitations.md | 60 +++++++++++++++++++++++++++++++++++++++
 v1.1/known-limitations.md | 60 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 120 insertions(+)

diff --git a/v1.0/known-limitations.md b/v1.0/known-limitations.md
index 14cf448a478..6028d2f6639 100644
--- a/v1.0/known-limitations.md
+++ b/v1.0/known-limitations.md
@@ -280,3 +280,63 @@ Also, a prepared [`INSERT`](insert.html), [`UPSERT`](upsert.html), or [`DELETE`]
 
 - If the number of columns has increased, the prepared statement returns an error but nonetheless writes the data.
 - If the number of columns remains the same but the types have changed, the prepared statement writes the data and does not return an error.
+
+## Dropping an index interleaved into another index on the same table
+
+In the unlikely case that you [interleave](interleave-in-parent.html) an index into another index on the same table and then [drop](drop-index.html) the interleaved index, future DDL operations on the table will fail.
+
+For example:
+
+~~~ sql
+> CREATE TABLE t1 (id1 INT PRIMARY KEY, id2 INT, id3 INT);
+~~~
+
+~~~ sql
+> CREATE INDEX c ON t1 (id2)
+      STORING (id1, id3)
+      INTERLEAVE IN PARENT t1 (id2);
+~~~
+
+~~~ sql
+> SHOW INDEXES FROM t1;
+~~~
+
+~~~
++-------+---------+--------+-----+--------+-----------+---------+----------+
+| Table |  Name   | Unique | Seq | Column | Direction | Storing | Implicit |
++-------+---------+--------+-----+--------+-----------+---------+----------+
+| t1    | primary | true   |   1 | id1    | ASC       | false   | false    |
+| t1    | c       | false  |   1 | id2    | ASC       | false   | false    |
+| t1    | c       | false  |   2 | id1    | N/A       | true    | false    |
+| t1    | c       | false  |   3 | id3    | N/A       | true    | false    |
++-------+---------+--------+-----+--------+-----------+---------+----------+
+(4 rows)
+~~~
+
+~~~ sql
+> DROP INDEX t1@c;
+~~~
+
+~~~ sql
+> DROP TABLE t1;
+~~~
+
+~~~
+pq: invalid interleave backreference table=t1 index=3: index-id "3" does not exist
+~~~
+
+~~~ sql
+> TRUNCATE TABLE t1;
+~~~
+
+~~~
+pq: invalid interleave backreference table=t1 index=3: index-id "3" does not exist
+~~~
+
+~~~ sql
+> ALTER TABLE t1 RENAME COLUMN id3 TO id4;
+~~~
+
+~~~
+pq: invalid interleave backreference table=t1 index=3: index-id "3" does not exist
+~~~
diff --git a/v1.1/known-limitations.md b/v1.1/known-limitations.md
index 8d0be283c06..c9fbfa6a059 100644
--- a/v1.1/known-limitations.md
+++ b/v1.1/known-limitations.md
@@ -201,3 +201,63 @@ Also, a prepared [`INSERT`](insert.html), [`UPSERT`](upsert.html), or [`DELETE`]
 
 - If the number of columns has increased, the prepared statement returns an error but nonetheless writes the data.
 - If the number of columns remains the same but the types have changed, the prepared statement writes the data and does not return an error.
+
+## Dropping an index interleaved into another index on the same table
+
+In the unlikely case that you [interleave](interleave-in-parent.html) an index into another index on the same table and then [drop](drop-index.html) the interleaved index, future DDL operations on the table will fail.
+
+For example:
+
+~~~ sql
+> CREATE TABLE t1 (id1 INT PRIMARY KEY, id2 INT, id3 INT);
+~~~
+
+~~~ sql
+> CREATE INDEX c ON t1 (id2)
+      STORING (id1, id3)
+      INTERLEAVE IN PARENT t1 (id2);
+~~~
+
+~~~ sql
+> SHOW INDEXES FROM t1;
+~~~
+
+~~~
++-------+---------+--------+-----+--------+-----------+---------+----------+
+| Table |  Name   | Unique | Seq | Column | Direction | Storing | Implicit |
++-------+---------+--------+-----+--------+-----------+---------+----------+
+| t1    | primary | true   |   1 | id1    | ASC       | false   | false    |
+| t1    | c       | false  |   1 | id2    | ASC       | false   | false    |
+| t1    | c       | false  |   2 | id1    | N/A       | true    | false    |
+| t1    | c       | false  |   3 | id3    | N/A       | true    | false    |
++-------+---------+--------+-----+--------+-----------+---------+----------+
+(4 rows)
+~~~
+
+~~~ sql
+> DROP INDEX t1@c;
+~~~
+
+~~~ sql
+> DROP TABLE t1;
+~~~
+
+~~~
+pq: invalid interleave backreference table=t1 index=3: index-id "3" does not exist
+~~~
+
+~~~ sql
+> TRUNCATE TABLE t1;
+~~~
+
+~~~
+pq: invalid interleave backreference table=t1 index=3: index-id "3" does not exist
+~~~
+
+~~~ sql
+> ALTER TABLE t1 RENAME COLUMN id3 TO id4;
+~~~
+
+~~~
+pq: invalid interleave backreference table=t1 index=3: index-id "3" does not exist
+~~~