-ES in NRT search framework.
- Only a small
latency from a document is indexed until it is searchable.
- Latency is of 1
second.
- Cluster consists
of nodes.
A mapping type is a way of separating the documents in an index into logical groups.
• MySQL => Databases => Tables => Columns/Rows
• Elasticsearch => Indices => Types => Documents with Properties
Aliases are
created for index.
An Index can have
multiple aliases.
Alias is used only
for reads operation.
Write operation
always point to index.
Read operation can hit and get result from replica as well.This way additional hardware to have more replicas will give better performance.
Updating shard is
not easy. While we create a
new index and reads will point to existing aliases pointing to new index.Write can’t do
such. For a short interval 20. Writes will fail and hence the health check will
fail.
Cat/_indices will
give the size of indexes
Primary needs to
be looked at. This will give sum of shards.
If we have
hierarchy in the mapping parent.child.child in the query could be costly. In
that case we can create a new node for
parent.child.child to have faster result.