[maven-release-plugin] prepare for next development iteration
diff --git a/cassandra/pom.xml b/cassandra/pom.xml
index dd101e4..3167efc 100644
--- a/cassandra/pom.xml
+++ b/cassandra/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.7.0</version>
+    <version>1.8.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-cassandra</artifactId>
   <packaging>jar</packaging>
-  <version>1.7.0</version>
+  <version>1.8.0-SNAPSHOT</version>
   <name>Calcite Cassandra</name>
   <description>Cassandra adapter for Calcite</description>
 
diff --git a/core/pom.xml b/core/pom.xml
index b4d0e34..9e6cdb2 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.7.0</version>
+    <version>1.8.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-core</artifactId>
   <packaging>jar</packaging>
-  <version>1.7.0</version>
+  <version>1.8.0-SNAPSHOT</version>
   <name>Calcite Core</name>
   <description>Core Calcite APIs and engine.</description>
 
diff --git a/example/csv/pom.xml b/example/csv/pom.xml
index 5c6076d..ed88b8a 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>1.7.0</version>
+    <version>1.8.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-example-csv</artifactId>
   <packaging>jar</packaging>
-  <version>1.7.0</version>
+  <version>1.8.0-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 29a8a80..120b6f5 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>1.7.0</version>
+    <version>1.8.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-example-function</artifactId>
   <packaging>jar</packaging>
-  <version>1.7.0</version>
+  <version>1.8.0-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 520294c..0714182 100644
--- a/example/pom.xml
+++ b/example/pom.xml
@@ -20,13 +20,13 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.7.0</version>
+    <version>1.8.0-SNAPSHOT</version>
   </parent>
 
   <!-- The basics. -->
   <artifactId>calcite-example</artifactId>
   <packaging>pom</packaging>
-  <version>1.7.0</version>
+  <version>1.8.0-SNAPSHOT</version>
   <name>Calcite Examples</name>
   <description>Calcite examples</description>
 
diff --git a/linq4j/pom.xml b/linq4j/pom.xml
index f965b7e..bda68c9 100644
--- a/linq4j/pom.xml
+++ b/linq4j/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.7.0</version>
+    <version>1.8.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-linq4j</artifactId>
   <packaging>jar</packaging>
-  <version>1.7.0</version>
+  <version>1.8.0-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 a49fe6e..ebae5a4 100644
--- a/mongodb/pom.xml
+++ b/mongodb/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.7.0</version>
+    <version>1.8.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-mongodb</artifactId>
   <packaging>jar</packaging>
-  <version>1.7.0</version>
+  <version>1.8.0-SNAPSHOT</version>
   <name>Calcite MongoDB</name>
   <description>MongoDB adapter for Calcite</description>
 
diff --git a/piglet/pom.xml b/piglet/pom.xml
index 0537575..9d2675f 100644
--- a/piglet/pom.xml
+++ b/piglet/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.7.0</version>
+    <version>1.8.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-piglet</artifactId>
   <packaging>jar</packaging>
-  <version>1.7.0</version>
+  <version>1.8.0-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 ec12545..4373acd 100644
--- a/plus/pom.xml
+++ b/plus/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.7.0</version>
+    <version>1.8.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-plus</artifactId>
   <packaging>jar</packaging>
-  <version>1.7.0</version>
+  <version>1.8.0-SNAPSHOT</version>
   <name>Calcite Plus</name>
   <description>Miscellaneous extras for Calcite</description>
 
diff --git a/pom.xml b/pom.xml
index af484e1..8b85be9 100644
--- a/pom.xml
+++ b/pom.xml
@@ -27,7 +27,7 @@
   <groupId>org.apache.calcite</groupId>
   <artifactId>calcite</artifactId>
   <packaging>pom</packaging>
-  <version>1.7.0</version>
+  <version>1.8.0-SNAPSHOT</version>
 
   <!-- More project information. -->
   <name>Calcite</name>
@@ -124,7 +124,7 @@
     <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-1.7.0</tag>
+    <tag>HEAD</tag>
   </scm>
 
   <modules>
diff --git a/spark/pom.xml b/spark/pom.xml
index 7807deb..7d40dc0 100644
--- a/spark/pom.xml
+++ b/spark/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.7.0</version>
+    <version>1.8.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-spark</artifactId>
   <packaging>jar</packaging>
-  <version>1.7.0</version>
+  <version>1.8.0-SNAPSHOT</version>
   <name>Calcite Spark</name>
 
   <properties>
diff --git a/splunk/pom.xml b/splunk/pom.xml
index 8816835..17d79fb 100644
--- a/splunk/pom.xml
+++ b/splunk/pom.xml
@@ -20,12 +20,12 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.7.0</version>
+    <version>1.8.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>calcite-splunk</artifactId>
   <packaging>jar</packaging>
-  <version>1.7.0</version>
+  <version>1.8.0-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 6701ed6..51739b3 100644
--- a/ubenchmark/pom.xml
+++ b/ubenchmark/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>org.apache.calcite</groupId>
     <artifactId>calcite</artifactId>
-    <version>1.7.0</version>
+    <version>1.8.0-SNAPSHOT</version>
   </parent>
 
   <properties>