Original: Guan Changlong

We have introduced six common segmentation algorithms of DBLE and MyCat through the previous six articles, so let's make a summary!

DBLE and MyCat corresponding algorithm name and similarities and differences

The seventh DBLE fragmentation algorithm jumpStringHash

In addition to the above six common sharding algorithms, DBLE also has a unique sharding algorithm: jump string algorithm.

The specific configuration is as follows:

#rule.xml
<function name="jumphash"
class="jumpStringHash">
<property name="partitionCount">2</property>
<property name="hashSlice">0:2</property>
</function>

partitionCont: number of segments

hashSlice: fragment cut length

This algorithm comes from a Google article "a fast, minimum memory, consistent hash algorithm". Its core idea is to change the probability of a hash value distribution in each node into 1/n by probability distribution method, and it can be calculated by a simpler method, and the distribution is more uniform.

At this point, we have finished the introduction of the seven fragmentation algorithms supported in DBLE. I believe that readers and friends are gradually familiar with the use of DBLE.

At the end of the series:

Full partition instance

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dble:rule SYSTEM "rule.dtd">
<dble:rule xmlns:dble="http://dble.cloud/" version="9.9.9.9">
<tableRule name="sharding-by-enum">
<rule>
<columns>id</columns>
<algorithm>enum</algorithm>
</rule>
</tableRule>
<tableRule name="sharding-by-range">
<rule>
<columns>id</columns>
<algorithm>rangeLong</algorithm>
</rule>
</tableRule>
<tableRule name="sharding-by-hash">
<rule>
<columns>id</columns>
<algorithm>hashLong</algorithm>
</rule>
</tableRule>
<tableRule name="sharding-by-hash2">
<rule>
<columns>id</columns>
<algorithm>hashLong2</algorithm>
</rule>
</tableRule>
<tableRule name="sharding-by-hash3">
<rule>
<columns>id</columns>
<algorithm>hashLong3</algorithm>
</rule>
</tableRule>
<tableRule name="sharding-by-mod">
<rule>
<columns>id</columns>
<algorithm>hashmod</algorithm>
</rule>
</tableRule>
<tableRule name="sharding-by-hash-str">
<rule>
<columns>id</columns>
<algorithm>hashString</algorithm>
</rule>
</tableRule>
<tableRule name="sharding-by-date">
<rule>
<columns>calldate</columns>
<algorithm>partbydate</algorithm>
</rule>
</tableRule>
<tableRule name="sharding-by-pattern">
<rule>
<columns>id</columns>
<algorithm>pattern</algorithm>
</rule>
</tableRule>
<!-- enum partition -->
<function name="enum"
class="Enum">
<property name="mapFile">partition-hash-int.txt</property>
<property name="defaultNode">0</property><!--the default is -1,means unexpected value will report error-->
<property name="type">0</property><!--0 means key is a number, 1 means key is a string-->
</function>
<!-- number range partition -->
<function name="rangeLong" class="NumberRange">
<property name="mapFile">autopartition-long.txt</property>
<property name="defaultNode">0</property><!--he default is -1,means unexpected value will report error-->
</function>
<!-- Hash partition,when partitionLength=1, it is a mod partition-->
<!--MAX(sum(count*length[i]) must not more then 2880-->
<function name="hashLong" class="Hash">
<property name="partitionCount">8</property>
<property name="partitionLength">12