From d19e2c7a8073a069f270e6f709e6cb075c0182d4 Mon Sep 17 00:00:00 2001
From: Jeremy Cole <jeremy@jcole.us>
Date: Fri, 18 Nov 2011 22:02:40 -0800
Subject: [PATCH] Perform a few SQL optimizations on nameserver access; clean
 up a bit.

The following migrations should be done to apply the indexing changes
and column order changes to existing nameservers:

ALTER TABLE shards
  CHANGE hostname
    hostname VARCHAR(125) NOT NULL AFTER class_name,
  ADD INDEX idx_busy (busy);

ALTER TABLE shard_children
  DROP INDEX child,
  ADD INDEX idx_parent (parent_hostname, parent_table_prefix, weight),
  ADD INDEX idx_child (child_hostname, child_table_prefix, weight);

ALTER TABLE forwardings
  CHANGE base_source_id
    base_source_id BIGINT NOT NULL AFTER table_id,
  DROP PRIMARY KEY,
  ADD PRIMARY KEY (table_id, base_source_id),
  DROP INDEX unique_shard,
  ADD UNIQUE uni_shard (shard_hostname, shard_table_prefix),
  ADD INDEX idx_updated  (updated_seq);

ALTER TABLE hosts
  DROP INDEX cluster,
  ADD INDEX idx_cluster (cluster, status);
---
 .../twitter/gizzard/nameserver/SqlShard.scala | 28 ++++++++++---------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/src/main/scala/com/twitter/gizzard/nameserver/SqlShard.scala b/src/main/scala/com/twitter/gizzard/nameserver/SqlShard.scala
index 5af05d16..7c9b7d1e 100644
--- a/src/main/scala/com/twitter/gizzard/nameserver/SqlShard.scala
+++ b/src/main/scala/com/twitter/gizzard/nameserver/SqlShard.scala
@@ -11,13 +11,14 @@ object SqlShard {
   val SHARDS_DDL = """
 CREATE TABLE IF NOT EXISTS shards (
     class_name              VARCHAR(125) NOT NULL,
+    hostname                VARCHAR(125) NOT NULL,
     table_prefix            VARCHAR(125) NOT NULL,
-    hostname                VARCHAR(125)  NOT NULL,
     source_type             VARCHAR(125),
     destination_type        VARCHAR(125),
     busy                    TINYINT      NOT NULL DEFAULT 0,
 
-   PRIMARY KEY (hostname, table_prefix)
+   PRIMARY KEY (hostname, table_prefix),
+   INDEX idx_busy (busy)
 ) ENGINE=INNODB
 """
 
@@ -30,22 +31,23 @@ CREATE TABLE IF NOT EXISTS shard_children (
     weight                  INT          NOT NULL DEFAULT 1,
 
     PRIMARY KEY (parent_hostname, parent_table_prefix, child_hostname, child_table_prefix),
-    INDEX child (child_hostname, child_table_prefix)
+    INDEX idx_parent (parent_hostname, parent_table_prefix, weight),
+    INDEX idx_child (child_hostname, child_table_prefix, weight)
 ) ENGINE=INNODB
 """
 
   val FORWARDINGS_DDL = """
 CREATE TABLE IF NOT EXISTS forwardings (
-    base_source_id          BIGINT                  NOT NULL,
     table_id                INT                     NOT NULL,
+    base_source_id          BIGINT                  NOT NULL,
     shard_hostname          VARCHAR(125)            NOT NULL,
     shard_table_prefix      VARCHAR(125)            NOT NULL,
     deleted                 TINYINT                 NOT NULL DEFAULT 0,
     updated_seq             BIGINT                  NOT NULL,
 
-    PRIMARY KEY         (base_source_id, table_id),
-    UNIQUE unique_shard (shard_hostname, shard_table_prefix),
-    INDEX  updated_seq  (updated_seq)
+    PRIMARY KEY (table_id, base_source_id),
+    UNIQUE uni_shard (shard_hostname, shard_table_prefix),
+    INDEX  idx_updated  (updated_seq)
 ) ENGINE=INNODB;
 """
 
@@ -66,7 +68,7 @@ CREATE TABLE IF NOT EXISTS hosts (
     status                  INT          NOT NULL DEFAULT 0,
 
     PRIMARY KEY (hostname, port),
-    INDEX cluster (cluster, status)
+    INDEX idx_cluster (cluster, status)
 ) ENGINE=INNODB;
 """
 }
@@ -95,8 +97,8 @@ class SqlShardManagerSource(queryEvaluator: QueryEvaluator) extends ShardManager
   def createShard(shardInfo: ShardInfo) {
     try {
       queryEvaluator.transaction { transaction =>
-        transaction.selectOne("SELECT * FROM shards WHERE table_prefix = ? AND hostname = ?",
-                              shardInfo.tablePrefix, shardInfo.hostname) { row =>
+        transaction.selectOne("SELECT * FROM shards WHERE hostname = ? AND table_prefix = ?",
+                              shardInfo.hostname, shardInfo.tablePrefix) { row =>
           if (row.getString("class_name") != shardInfo.className ||
               row.getString("source_type") != shardInfo.sourceType ||
               row.getString("destination_type") != shardInfo.destinationType) {
@@ -300,8 +302,8 @@ class SqlShardManagerSource(queryEvaluator: QueryEvaluator) extends ShardManager
   }
 
   def getForwarding(tableId: Int, baseId: Long) = {
-    val query = "SELECT * FROM forwardings WHERE base_source_id = ? AND table_id = ? AND deleted = 0"
-    queryEvaluator.selectOne(query, baseId, tableId)(rowToForwarding) getOrElse { throw new ShardException("No such forwarding") }
+    val query = "SELECT * FROM forwardings WHERE table_id = ? AND base_source_id = ? AND deleted = 0"
+    queryEvaluator.selectOne(query, tableId, baseId)(rowToForwarding) getOrElse { throw new ShardException("No such forwarding") }
   }
 
   def getForwardingForShard(id: ShardId) = {
@@ -322,7 +324,7 @@ class SqlShardManagerSource(queryEvaluator: QueryEvaluator) extends ShardManager
   }
 
   def getBusyShards() = {
-    queryEvaluator.select("SELECT * FROM shards where busy != 0")(rowToShardInfo).toList
+    queryEvaluator.select("SELECT * FROM shards where busy IN (1, 2, 3)")(rowToShardInfo).toList
   }
 
   def reload() {