Overview

With Swarm 16.1.2 and Gateway 8.1.0, we introduced a new feature called “Per Domain Index”. We can now store metadata from each domain in separate indices within our Elasticsearch database. This feature allows for more efficient searching, querying, and retrieval of objects within a specific domain. It is enabled by setting search.perDomainIndex=True before creating a search feed. You can enable this setting using any of the following options:

• scsctl
  scsctl storage config set -d "search.perDomainIndex=true"
scsctl storage config set -d "search.numberOfShards=5"

• swarmctl
  swarmctl -C search.perDomainIndex -V 1 -a -p username:password

• Storage UI

  Open

  

Data in Elasticsearch is organized into indices. Each index is made up of one or more shards. Each shard is an instance of a Lucene index, which you can think of as a self-contained search engine that indexes and handles queries for a subset of the data in an Elasticsearch cluster.

Key benefits of the Per Domain Index include:

1. Improved Search Performance: By indexing objects within a domain, searches can be limited to the domain, reducing the search scope and speeding up retrieval.

2. Granular Data Management: Each domain can have its index, allowing administrators to manage indexing based on domain-specific needs.

3. Scalability: As the number of objects grows, having separate indices for each domain helps in scaling the system without performance degradation.

Per Domain Index is useful in multi-tenant environments, where each tenant (domain) may need separate indexing to optimize their storage and access.

With Per Domain Index (PDI), customers are separated by different domains and use distinct indices. As a result, the latency for each domain is directly related to the number of documents in its respective index, allowing for more efficient performance management.

Prerequisites

• Gateway 8.1.0 or higher

• Swarm Storage 16.1.2 or higher

Hardware Sizing

• Shard Size: Recommended shard size is between 20 GB and 50 GB.

• Shard Alignment: Align the number of shards with the number of nodes (shards should be a multiple of nodes).

• Heap Size: Maximum heap size of 30.5 GB per node.

• Shard Capacity: A node can handle up to 30.5 GB heap * 20 shards per GB of heap, resulting in a maximum of approximately 600 shards per node.

• Elastic Limit: Elasticsearch has a default maximum shard limit of 1,000 per node. It is advisable to stay below 600 shards per node for optimal performance.

How to Implement/Enable in Production

Implementing PDI requires the following configurations:

• Set search.numberOfShards = 5 to optimize performance and avoid exceeding the 600 shards per Elasticsearch node limit.

• Set search.perDomainIndex = True in the cluster configuration before creating the Search Feed.

• Create a new search feed and make it default. Once the search feed is 100% indexed, it will automatically create separate indices for each domain. For example, index_clustername_feedid_domainUUID.

Implementing Per Domain Index (PDI) Without Downtime

1. Keep the new search feed index at 100% after PDI is enabled: When enabling PDI, a new set of indices is created, each corresponding to a specific domain. The new search feed needs to be fully populated (100%) before switching to those indices. This means that all contexts and objects are indexed without any gaps or missing data.

2. Once completed, set the new search feed as the default: When the search feed is 100%, remember to verify indexerHosts in gateway.cfg and restart Gateways whenever the default Search Feed is changed. Now, the cluster is ready to list as per PDI. This switch should be seamless to ensure that users experience no disruption.

3. Clean up the previous index (created without PDI) as needed: The old index stored data without per-domain segregation is now redundant. Cleaning it up can free up resources and reduce storage costs.

Implementing Per Domain Index (PDI) With Downtime

1. Set the new search feed as the default after enabling PDI: If downtime is acceptable, the process is simpler. You can immediately switch to the new search feed after enabling PDI, even if they are not fully populated. Users will experience downtime or incomplete search results until reindexing is complete.

2. The new index will be temporarily unavailable for listing: During reindexing, the new domain indices may not be fully operational. Users may experience missing or incomplete data in search results.

3. Listing will resume after the new search feed reaches 100% completion: Once the reindexing is complete, the search functionality will return to full capacity with complete and accurate listings.

Disabling Per Domain Index

1. Set search.perDomainIndex = False and delete the associated Search Feed: To disable PDI, switch the configuration setting that enables search.perDomainIndex to False. This setting controls whether the next Search Feed that is created should use per-domain indices or not. After disabling, delete all per-domain search feeds to delete all the per-domain indices.

2. All Per Domain Indices will be removed: After disabling PDI, the system will revert to using a single index for all domains. This simplifies data management but loses the benefits of domain-specific indexing.

Limitations

• Increased Complexity: Managing multiple indexes can complicate the architecture of the search engine or database system. It requires more sophisticated algorithms and infrastructure to handle indexing and searching across domains.

• Resource Intensive: Each index requires storage space and processing power. Maintaining multiple indexes can lead to higher resource consumption, increasing costs for hardware, maintenance, and energy.

• Index Synchronization: Keeping indexes up-to-date across multiple domains can be challenging. Changes in the data must be reflected in all relevant indexes, which can introduce delays or errors.

• Scalability Issues: As the number of domains increases, scaling the infrastructure to support numerous indexes can become difficult. Performance may suffer if not properly managed.

How to Determine PDI is Working

Search Feed Schema

• When search.perDomainIndex = False, the schema will have a null_value of "2.1".

• When search.perDomainIndex = True, the schema will have a null_value of "3.0".

Per Domain Index

This command will list all indices for each domain in the cluster.