Clean up memcached dependencies.

These are no longer needed after vitessio#1742.

Author: Anthony Yeh

.travis.yml

@@ -11,7 +11,6 @@ addons:
       # NOTE: When you add a dependency, don't forget to add comment why it's necessary.
       - automake
       - libtool
-      - memcached
       - php5-cli
       - php5-dev
       - python-dev

doc/GettingStarted.md

@@ -100,7 +100,6 @@ In addition, Vitess requires the software and libraries listed below.
     - make
     - automake
     - libtool
-    - memcached
     - python-dev
     - python-virtualenv
     - python-mysqldb
@@ -116,7 +115,7 @@ In addition, Vitess requires the software and libraries listed below.
     These can be installed with the following apt-get command:
 
     ``` sh
-    $ sudo apt-get install make automake libtool memcached python-dev python-virtualenv python-mysqldb libssl-dev g++ mercurial git pkg-config bison curl unzip
+    $ sudo apt-get install make automake libtool python-dev python-virtualenv python-mysqldb libssl-dev g++ mercurial git pkg-config bison curl unzip
     ```
 
 5.  If you decided to use ZooKeeper in step 3, you also need to install a
@@ -152,7 +151,7 @@ In addition, Vitess requires the software and libraries listed below.
 5.  Run the following commands:
 
     ``` sh
-    brew install go automake libtool memcached python mercurial git bison curl wget homebrew/versions/mysql56
+    brew install go automake libtool python mercurial git bison curl wget homebrew/versions/mysql56
     pip install --upgrade pip setuptools
     pip install virtualenv
     pip install MySQL-python

doc/Reparenting.md

@@ -125,7 +125,6 @@ This command performs the following actions:
 1. Promotes the master-elect tablet to be the new master. In addition to
    changing its tablet type to <code>master</code>, the master-elect
    performs any other changes that might be required for its new state.
-   For example, it might need to modify the way its rowcache works.
 1. Ensures replication is functioning properly via the following steps:
    1.  On the master-elect tablet, Vitess inserts an entry in a test table
        and then updates the <code>MasterAlias</code> record of the global

doc/V3HighLevelDesign.md

@@ -1521,7 +1521,7 @@ Join
 select :_a_col+b.col from b where b.foo=:_a_bar
 ```
 
-*However, such queries are not very efficient for VTTablet. It can’t cache field info, or use rowcache. Such push-downs don’t benefit MySQL either. So, it’s better to wait till VTGate implements the ability to evaluate expressions.*
+*However, such queries are not very efficient for VTTablet. It can’t cache field info. Such push-downs don’t benefit MySQL either. So, it’s better to wait till VTGate implements the ability to evaluate expressions.*
 
 SELECT can also contain subqueries. The same restriction as WHERE clauses can be applied here: If the keyspace id of the subquery is not the same as the outer query’s, we fail the query. Otherwise, we push it down.
 

doc/Vision.md

@@ -19,10 +19,9 @@ kind of scalability that NoSQL databases provide.
 ### Priorities
 
 * *Scalability*: This is achieved by replication and sharding.
-* *Efficiency*: This is achieved by a proxy server (vttablet) that mediates
-all queries and connections.
-It also utilizes a more efficient rowcache to short-cut some of the queries.
-This effectively increases a typical MySQL's serving capacity.
+* *Efficiency*: This is achieved by a proxy server (vttablet) that
+multiplexes queries into a fixed-size connection pool, and rewrites
+updates by primary key to speed up slave applier threads.
 * *Manageability*: As soon as you add replication and sharding that span
 across multiple data centers, the number of servers spirals out of control.
 Vitess provides a set of tools backed by a lockserver (zookeeper) to

doc/VitessOverview.md

@@ -86,7 +86,6 @@ If you're considering a NoSQL solution primarily because of concerns about the s
   * Connection pooling - Scale front-end connections while optimizing MySQL performance.
   * Query de-duping – Reuse results of an in-flight query for any identical requests received while the in-flight query was still executing.
   * Transaction manager – Limit number of concurrent transactions and manage deadlines to optimize overall throughput.
-  * Rowcache – Maintain a row-based cache (using memcached) to more efficiently field queries that require random access by primary key, very useful for OLTP workloads. (The MySQL buffer cache is optimized for range scans over indices and tables.). This can replace a custom caching layer implementation at the application layer.<br><br>
 
 * **Protection**
 
@@ -117,7 +116,7 @@ The Vitess platform consists of a number of server processes, command-line utili
 
 Depending on the current state of your application, you could arrive at a full Vitess implementation through a number of different process flows. For example, if you're building a service from scratch, your first step with Vitess would be to define your database topology. However, if you need to scale your existing database, you'd likely start by deploying a connection proxy.
 
-Vitess tools and servers are designed to help you whether you start with a complete fleet of databases or start small and scale over time. For smaller implementations, vttablet features like connection pooling and rowcache help you get more from your existing hardware. Vitess' automation tools then provide additional benefits for larger implementations.
+Vitess tools and servers are designed to help you whether you start with a complete fleet of databases or start small and scale over time. For smaller implementations, vttablet features like connection pooling and query rewriting help you get more from your existing hardware. Vitess' automation tools then provide additional benefits for larger implementations.
 
 The diagram below illustrates Vitess' components:
 

docker/bootstrap/Dockerfile.common

@@ -11,7 +11,6 @@ RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-ins
     libssl-dev \
     libtool \
     make \
-    memcached \
     mercurial \
     openjdk-7-jdk \
     php-pear \

docker/lite/Dockerfile

@@ -8,7 +8,6 @@ RUN apt-key adv --recv-keys --keyserver pgp.mit.edu 5072E1F5 \
  && DEBIAN_FRONTEND=noninteractive \
     apt-get install -y --no-install-recommends \
       bzip2 \
-      memcached \
       libmysqlclient18 \
       mysql-client \
       mysql-server \

docker/lite/Dockerfile.mariadb

@@ -7,7 +7,6 @@ RUN apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 0xcbcb082a1bb943db
  && apt-get update \
  && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
       bzip2 \
-      memcached \
       mariadb-server \
  && rm -rf /var/lib/apt/lists/*
 

docker/lite/Dockerfile.mysql56

@@ -8,7 +8,6 @@ RUN apt-key adv --recv-keys --keyserver pgp.mit.edu 5072E1F5 \
  && DEBIAN_FRONTEND=noninteractive \
     apt-get install -y --no-install-recommends \
       bzip2 \
-      memcached \
       libmysqlclient18 \
       mysql-client \
       mysql-server \