diff --git a/cassandra/pom.xml b/cassandra/pom.xml
index 365f3be..5d1f4fd 100644
--- a/cassandra/pom.xml
+++ b/cassandra/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-cassandra</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Cassandra</name>
   <description>Cassandra adapter for Calcite</description>
 
diff --git a/core/pom.xml b/core/pom.xml
index 7bfbcd1..73c1866 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-core</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Core</name>
   <description>Core Calcite APIs and engine.</description>
 
diff --git a/druid/pom.xml b/druid/pom.xml
index eeb7002..f327221 100644
--- a/druid/pom.xml
+++ b/druid/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-druid</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Druid</name>
   <description>Druid adapter for Calcite</description>
 
diff --git a/elasticsearch2/pom.xml b/elasticsearch2/pom.xml
index 20e9f7e..67f56a7 100644
--- a/elasticsearch2/pom.xml
+++ b/elasticsearch2/pom.xml
@@ -21,12 +21,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-elasticsearch2</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Elasticsearch</name>
   <description>Elasticsearch adapter for Calcite</description>
 
diff --git a/elasticsearch5/pom.xml b/elasticsearch5/pom.xml
index 9714e9c..184e12d 100644
--- a/elasticsearch5/pom.xml
+++ b/elasticsearch5/pom.xml
@@ -21,12 +21,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-elasticsearch5</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Elasticsearch5</name>
   <description>Elasticsearch5 adapter for Calcite</description>
 
diff --git a/example/csv/pom.xml b/example/csv/pom.xml
index caa6251..71cff33 100644
--- a/example/csv/pom.xml
+++ b/example/csv/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite-example</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-example-csv</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Example CSV</name>
   <description>An example Calcite provider that reads CSV files</description>
 
diff --git a/example/function/pom.xml b/example/function/pom.xml
index b011b96..01eec8d 100644
--- a/example/function/pom.xml
+++ b/example/function/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite-example</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-example-function</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Example Function</name>
   <description>Examples of user-defined Calcite functions</description>
 
diff --git a/example/pom.xml b/example/pom.xml
index 33b013c..965d3b7 100644
--- a/example/pom.xml
+++ b/example/pom.xml
@@ -20,13 +20,13 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <!-- The basics. -->
   <artifactId>calcite-example</artifactId>
   <packaging>pom</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Examples</name>
   <description>Calcite examples</description>
 
diff --git a/file/pom.xml b/file/pom.xml
index 1ce723e..6ea7f08 100644
--- a/file/pom.xml
+++ b/file/pom.xml
@@ -19,13 +19,13 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <!-- The basics. -->
   <artifactId>calcite-file</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite File</name>
   <description>Calcite provider that reads files and URIs</description>
 
diff --git a/linq4j/pom.xml b/linq4j/pom.xml
index 44ed858..c57a34f 100644
--- a/linq4j/pom.xml
+++ b/linq4j/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-linq4j</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Linq4j</name>
   <description>Calcite APIs for LINQ (Language-Integrated Query) in Java</description>
 
diff --git a/mongodb/pom.xml b/mongodb/pom.xml
index d96301f..8216f0a 100644
--- a/mongodb/pom.xml
+++ b/mongodb/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-mongodb</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite MongoDB</name>
   <description>MongoDB adapter for Calcite</description>
 
diff --git a/pig/pom.xml b/pig/pom.xml
index 82ca1b9..50763c9 100644
--- a/pig/pom.xml
+++ b/pig/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-pig</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Pig</name>
   <description>Pig adapter for Calcite</description>
 
diff --git a/piglet/pom.xml b/piglet/pom.xml
index 9d27801..6194116 100644
--- a/piglet/pom.xml
+++ b/piglet/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-piglet</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Piglet</name>
   <description>Pig-like language built on top of Calcite algebra</description>
 
diff --git a/plus/pom.xml b/plus/pom.xml
index 81dcb9f..2e7b54d 100644
--- a/plus/pom.xml
+++ b/plus/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-plus</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Plus</name>
   <description>Miscellaneous extras for Calcite</description>
 
diff --git a/pom.xml b/pom.xml
index 8bd7d85..6b76026 100644
--- a/pom.xml
+++ b/pom.xml
@@ -27,7 +27,7 @@
   <groupId>org.apache.calcite</groupId>
   <artifactId>calcite</artifactId>
   <packaging>pom</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
 
   <!-- More project information. -->
   <name>Calcite</name>
@@ -134,7 +134,7 @@
     <connection>scm:git:https://git-wip-us.apache.org/repos/asf/calcite.git</connection>
     <developerConnection>scm:git:https://git-wip-us.apache.org/repos/asf/calcite.git</developerConnection>
     <url>https://github.com/apache/calcite</url>
-    <tag>calcite-1.14.0</tag>
+    <tag>HEAD</tag>
   </scm>
 
   <modules>
diff --git a/spark/pom.xml b/spark/pom.xml
index 7f77ee0..dee2440 100644
--- a/spark/pom.xml
+++ b/spark/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-spark</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Spark</name>
 
   <properties>
diff --git a/splunk/pom.xml b/splunk/pom.xml
index 5381aa7..1aec77d 100644
--- a/splunk/pom.xml
+++ b/splunk/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-splunk</artifactId>
   <packaging>jar</packaging>
-  <version>1.14.0</version>
+  <version>1.15.0-SNAPSHOT</version>
   <name>Calcite Splunk</name>
   <description>Splunk adapter for Calcite; also a JDBC driver for Splunk</description>
 
diff --git a/ubenchmark/pom.xml b/ubenchmark/pom.xml
index f245321..3a33326 100644
--- a/ubenchmark/pom.xml
+++ b/ubenchmark/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.14.0</version>
+    <version>1.15.0-SNAPSHOT</version>
   </parent>
 
   <properties>