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Table Of Contents
vFabric SQLFire Glossary
bucket
The container for data that determines its storage site (or sites when there is redundancy), and the unit of migration
for rebalancing.
colocation
A relationship between two tables whereby the buckets that correspond to the same values of their partitioning
elds are guaranteed to be physically located in the same server or peer. In SQLFire, a table congured to be
colocated with another table has a dependency on the other table. If the other table needs to be dropped, then
the colocated tables must to be dropped rst.
data store
A FabricServer or a peer client process that is connected to the distributed system and has the host-data
property set to true. A data store is automatically part of the default server group, and may be congured to be
part of other server groups.
default colocation
A colocation relationship that is set up automatically between tables when there is no COLOCATED WITH
clause in the CREATE TABLE statement. The default colocation policy is described here.
default server group
The anonymous server group that implicitly includes all server in the distributed system. This is the server group
that hosts the data for a table where there is no SERVER GROUPS clause in the CREATE TABLE statement,
and there were no server groups specied in the CREATE SCHEMA statement for the schema that this table
belongs to.
distributed system
A typical SQLFire deployment is made up of a number of distributed processes that connect to each other to
form a peer to peer network. These member processes may or may not host any data. The GemFire JDBC client
process and all fabric servers are always peer members of the distributed system. The members discover each
other dynamically through a built-in multicast based discovery mechanism or using the GemFire locator service
when TCP is more desirable. Sometimes a distributed system is also referred to as a SQLFire cluster.
hash-partitioning
A partitioning strategy based on the hashcode of one or more elds, such that all the values with the same
hashcode are placed into the same bucket.
horizontal vs. vertical partitioning
Horizontal partitioning refers to partitioning strategy where a table is split by rows so that a bucket always
contains entire rows. Vertical partitioning refers to strategies where a table is split by columns so that a bucket
always contains entire columns. SQLFire currently only supports horizontal partitioning strategies.
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