Share this
Postgres partial indexes on email address domains
by Valerie Parham-Thompson on Aug 20, 2020 12:00:00 AM
Populate data
The test data has mostly email addresses from a large known domain. Our test data is only in the low millions, but it will give us enough to work with. The percentage column was created with random() so we can use it for domain population. Names were imported from sample data at https://github.com/solvenium/names-dataset.update users set email=concat(name, '@gmail.com') where percentage>.20; UPDATE 3060977And some from another known domain.
update users set email=concat(name, '@yahoo.com') where email not like '%gmail.com'; UPDATE 763903Finally, a small handful of email addresses from our target domain.
update users set email=concat(name, '@aol.com') where percentage<.0005; UPDATE 1841
No index
Trust me, this takes a lot longer when row counts are in the billions.postgres=# explain analyze verbose select * from users where email like '%aol.com'; QUERY PLAN ---------------------------------------------------- Gather (cost=1000.00..53368.45 rows=382 width=35) (actual time=2.058..453.503 rows=1841 loops=1) Output: name, email, percentage Workers Planned: 2 Workers Launched: 2 -> Parallel Seq Scan on public.users (cost=0.00..52330.25 rows=159 width=35) (actual time=0.478..339.496 rows=614 loops=3) Output: name, email, percentage Filter: ((users.email)::text ~~ '%aol.com'::text) Rows Removed by Filter: 1274346 Worker 0: actual time=0.151..279.486 rows=349 loops=1 Worker 1: actual time=0.040..289.677 rows=737 loops=1 Planning Time: 0.301 ms Execution Time: 453.742 ms (12 rows)
Create index
This index isn't going to help due to the left-most wildcard, but let's prove it.create index idx_user_email on users(email); CREATE INDEX postgres=# explain analyze verbose select * from users where email like '%aol.com'; QUERY PLAN ------------------------------------------------------------- Gather (cost=1000.00..53368.45 rows=382 width=35) (actual time=2.775..455.128 rows=1841 loops=1) Output: name, email, percentage Workers Planned: 2 Workers Launched: 2 -> Parallel Seq Scan on public.users (cost=0.00..52330.25 rows=159 width=35) (actual time=0.714..343.353 rows=614 loops=3) Output: name, email, percentage Filter: ((users.email)::text ~~ '%aol.com'::text) Rows Removed by Filter: 1274346 Worker 0: actual time=0.140..279.955 rows=311 loops=1 Worker 1: actual time=0.123..299.223 rows=823 loops=1 Planning Time: 0.306 ms Execution Time: 455.387 ms (12 rows)
Create like index
This was my first idea for a partial index. Partial indexes, briefly, let you leverage a "where" clause in the index itself. The results were impressive.create index idx_user_domain on users(email) where email like '%aol.com'; CREATE INDEX explain analyze verbose select * from users where email like '%aol.com'; QUERY PLAN ---------------------------------------------------------------- Bitmap Heap Scan on public.users (cost=14.28..1415.62 rows=382 width=35) (actual time=1.917..14.224 rows=1841 loops=1) Output: name, email, percentage Recheck Cond: ((users.email)::text ~~ '%aol.com'::text) Heap Blocks: exact=1602 -> Bitmap Index Scan on idx_user_domain (cost=0.00..14.19 rows=382 width=0) (actual time=0.988..0.989 rows=1841 loops=1) Planning Time: 1.849 ms Execution Time: 14.331 ms (7 rows)
Reverse
One of the problems in searching for domains in email addresses has to do with the variable length of strings before the "@" symbol. This is why the wildcard is needed. A common trick is to reverse the email string to force a more standard length. Without rewriting the reversed string and indexing it, you're still looking at a sequential scan.postgres=# explain analyze verbose select email from users where left(reverse(email::text),8)='moc.loa'; QUERY PLAN ------------------------------------------------------------- Gather (cost=1000.00..63211.15 rows=19124 width=17) (actual time=593.064..596.289 rows=0 loops=1) Output: email Workers Planned: 2 Workers Launched: 2 -> Parallel Seq Scan on public.users (cost=0.00..60298.75 rows=7968 width=17) (actual time=547.845..547.846 rows=0 loops=3) Output: email Filter: ("left"(reverse((users.email)::text), 8) = 'moc.loa'::text) Rows Removed by Filter: 1274960 Worker 0: actual time=526.251..526.251 rows=0 loops=1 Worker 1: actual time=526.283..526.283 rows=0 loops=1 Planning Time: 0.548 ms Execution Time: 596.420 ms (12 rows)What if we combined a partial index with this idea?
create index idx_user_reverse on users(email) where left(reverse(email::text),8)='moc.loa'; explain analyze verbose select email from users where left(reverse(email::text),8)='moc.loa'; QUERY PLAN ------------------------------------------------------------ Bitmap Heap Scan on public.users (cost=8.91..29508.71 rows=19124 width=17) (actual time=0.004..0.005 rows=0 loops=1) Output: email Recheck Cond: ("left"(reverse((users.email)::text), 8) = 'moc.loa'::text) -> Bitmap Index Scan on idx_user_reverse (cost=0.00..4.13 rows=19124 width=0) (actual time=0.002..0.002 rows=0 loops=1) Planning Time: 0.534 ms Execution Time: 0.025 ms (6 rows)Oh, yes. Very nice.
Share this
- Technical Track (967)
- Oracle (412)
- MySQL (140)
- Cloud (128)
- Microsoft SQL Server (117)
- Open Source (90)
- Google Cloud (81)
- Microsoft Azure (63)
- Amazon Web Services (AWS) (58)
- Big Data (52)
- Google Cloud Platform (46)
- Cassandra (44)
- DevOps (41)
- Pythian (33)
- Linux (30)
- Database (26)
- Performance (25)
- Podcasts (25)
- Site Reliability Engineering (25)
- PostgreSQL (24)
- Oracle E-Business Suite (23)
- Oracle Database (22)
- Docker (21)
- DBA (20)
- Security (20)
- Exadata (18)
- MongoDB (18)
- Oracle Cloud Infrastructure (OCI) (18)
- Oracle Exadata (18)
- Automation (17)
- Hadoop (16)
- Oracleebs (16)
- Amazon RDS (15)
- Ansible (15)
- Snowflake (15)
- ASM (13)
- Artificial Intelligence (AI) (13)
- BigQuery (13)
- Replication (13)
- Advanced Analytics (12)
- Data (12)
- GenAI (12)
- Kubernetes (12)
- LLM (12)
- Authentication, SSO and MFA (11)
- Cloud Migration (11)
- Machine Learning (11)
- Rman (11)
- Datascape Podcast (10)
- Monitoring (10)
- Oracle Applications (10)
- Apache Cassandra (9)
- ChatGPT (9)
- Data Guard (9)
- Infrastructure (9)
- Python (9)
- Series (9)
- AWR (8)
- High Availability (8)
- Oracle EBS (8)
- Oracle Enterprise Manager (OEM) (8)
- Percona (8)
- Apache Beam (7)
- Data Governance (7)
- Innodb (7)
- Microsoft Azure SQL Database (7)
- Migration (7)
- Myrocks (7)
- Performance Tuning (7)
- Data Enablement (6)
- Data Visualization (6)
- Database Performance (6)
- Oracle Enterprise Manager (6)
- Orchestrator (6)
- RocksDB (6)
- Serverless (6)
- Azure Data Factory (5)
- Azure Synapse Analytics (5)
- Covid-19 (5)
- Disaster Recovery (5)
- Generative AI (5)
- Google BigQuery (5)
- Mariadb (5)
- Microsoft (5)
- Scala (5)
- Windows (5)
- Xtrabackup (5)
- Airflow (4)
- Analytics (4)
- Apex (4)
- Cloud Security (4)
- Cloud Spanner (4)
- CockroachDB (4)
- Data Management (4)
- Data Pipeline (4)
- Data Security (4)
- Data Strategy (4)
- Database Administrator (4)
- Database Management (4)
- Database Migration (4)
- Dataflow (4)
- Fusion Middleware (4)
- Google (4)
- Oracle Autonomous Database (Adb) (4)
- Oracle Cloud (4)
- Prometheus (4)
- Redhat (4)
- Slob (4)
- Ssl (4)
- Terraform (4)
- Amazon Relational Database Service (Rds) (3)
- Apache Kafka (3)
- Apexexport (3)
- Aurora (3)
- Business Intelligence (3)
- Cloud Armor (3)
- Cloud Database (3)
- Cloud FinOps (3)
- Cosmos Db (3)
- Data Analytics (3)
- Data Integration (3)
- Database Monitoring (3)
- Database Troubleshooting (3)
- Database Upgrade (3)
- Databases (3)
- Dataops (3)
- Digital Transformation (3)
- ERP (3)
- Google Chrome (3)
- Google Cloud Sql (3)
- Google Workspace (3)
- Graphite (3)
- Heterogeneous Database Migration (3)
- Liquibase (3)
- Oracle Data Guard (3)
- Oracle Live Sql (3)
- Oracle Rac (3)
- Perl (3)
- Rdbms (3)
- Remote Teams (3)
- S3 (3)
- SAP (3)
- Tensorflow (3)
- Adf (2)
- Adop (2)
- Amazon Data Migration Service (2)
- Amazon Ec2 (2)
- Amazon S3 (2)
- Apache Flink (2)
- Ashdump (2)
- Atp (2)
- Autonomous (2)
- Awr Data Mining (2)
- Cloud Cost Optimization (2)
- Cloud Data Fusion (2)
- Cloud Hosting (2)
- Cloud Infrastructure (2)
- Cloud Shell (2)
- Cloud Sql (2)
- Conferences (2)
- Cosmosdb (2)
- Cost Management (2)
- Cyber Security (2)
- Data Analysis (2)
- Data Discovery (2)
- Data Engineering (2)
- Data Migration (2)
- Data Modeling (2)
- Data Quality (2)
- Data Streaming (2)
- Data Warehouse (2)
- Database Consulting (2)
- Database Migrations (2)
- Dataguard (2)
- Docker-Composer (2)
- Enterprise Data Platform (EDP) (2)
- Etl (2)
- Events (2)
- Gemini (2)
- Health Check (2)
- Infrastructure As Code (2)
- Innodb Cluster (2)
- Innodb File Structure (2)
- Innodb Group Replication (2)
- NLP (2)
- Neo4J (2)
- Nosql (2)
- Open Source Database (2)
- Oracle Datase (2)
- Oracle Extended Manager (Oem) (2)
- Oracle Flashback (2)
- Oracle Forms (2)
- Oracle Installation (2)
- Oracle Io Testing (2)
- Podcast (2)
- Power Bi (2)
- Redshift (2)
- Remote DBA (2)
- Remote Sre (2)
- SAP HANA Cloud (2)
- Single Sign-On (2)
- Webinars (2)
- X5 (2)
- Actifio (1)
- Adf Custom Email (1)
- Adrci (1)
- Advanced Data Services (1)
- Afd (1)
- Ahf (1)
- Alloydb (1)
- Amazon (1)
- Amazon Athena (1)
- Amazon Aurora Backtrack (1)
- Amazon Efs (1)
- Amazon Redshift (1)
- Amazon Sagemaker (1)
- Amazon Vpc Flow Logs (1)
- Analysis (1)
- Analytical Models (1)
- Anisble (1)
- Anthos (1)
- Apache (1)
- Apache Nifi (1)
- Apache Spark (1)
- Application Migration (1)
- Ash (1)
- Asmlib (1)
- Atlas CLI (1)
- Awr Mining (1)
- Aws Lake Formation (1)
- Azure Data Lake (1)
- Azure Data Lake Analytics (1)
- Azure Data Lake Store (1)
- Azure Data Migration Service (1)
- Azure OpenAI (1)
- Azure Sql Data Warehouse (1)
- Batches In Cassandra (1)
- Business Insights (1)
- Chown (1)
- Chrome Security (1)
- Cloud Browser (1)
- Cloud Build (1)
- Cloud Consulting (1)
- Cloud Data Warehouse (1)
- Cloud Database Management (1)
- Cloud Dataproc (1)
- Cloud Foundry (1)
- Cloud Manager (1)
- Cloud Networking (1)
- Cloud SQL Replica (1)
- Cloud Scheduler (1)
- Cloud Services (1)
- Cloud Strategies (1)
- Compliance (1)
- Conversational AI (1)
- DAX (1)
- Data Analytics Platform (1)
- Data Box (1)
- Data Classification (1)
- Data Cleansing (1)
- Data Encryption (1)
- Data Estate (1)
- Data Flow Management (1)
- Data Insights (1)
- Data Integrity (1)
- Data Lake (1)
- Data Leader (1)
- Data Lifecycle Management (1)
- Data Lineage (1)
- Data Masking (1)
- Data Mesh (1)
- Data Migration Assistant (1)
- Data Migration Service (1)
- Data Mining (1)
- Data Monetization (1)
- Data Policy (1)
- Data Profiling (1)
- Data Protection (1)
- Data Retention (1)
- Data Safe (1)
- Data Sheets (1)
- Data Summit (1)
- Data Vault (1)
- Data Warehouse Modernization (1)
- Database Auditing (1)
- Database Consultant (1)
- Database Link (1)
- Database Modernization (1)
- Database Provisioning (1)
- Database Provisioning Failed (1)
- Database Replication (1)
- Database Scaling (1)
- Database Schemas (1)
- Database Security (1)
- Databricks (1)
- Datascape 59 (1)
- DeepSeek (1)
- Duet AI (1)
- Edp (1)
- Gcp Compute (1)
- Gcp-Spanner (1)
- Global Analytics (1)
- Google Analytics (1)
- Google Cloud Architecture Framework (1)
- Google Cloud Data Services (1)
- Google Cloud Partner (1)
- Google Cloud Spanner (1)
- Google Cloud VMware Engine (1)
- Google Compute Engine (1)
- Google Dataflow (1)
- Google Datalab (1)
- Google Grab And Go (1)
- Graph Algorithms (1)
- Graph Databases (1)
- Graph Inferences (1)
- Graph Theory (1)
- GraphQL (1)
- Healthcheck (1)
- Information (1)
- Infrastructure As A Code (1)
- Innobackupex (1)
- Innodb Concurrency (1)
- Innodb Flush Method (1)
- It Industry (1)
- Kubeflow (1)
- LMSYS Chatbot Arena (1)
- Linux Host Monitoring (1)
- Linux Storage Appliance (1)
- Looker (1)
- MMLU (1)
- Managed Services (1)
- Migrate (1)
- Migrating Ssis Catalog (1)
- Migration Checklist (1)
- MongoDB Atlas (1)
- MongoDB Compass (1)
- Newsroom (1)
- Nifi (1)
- OPEX (1)
- ORAPKI (1)
- Odbcs (1)
- Odbs (1)
- On-Premises (1)
- Ora-01852 (1)
- Ora-7445 (1)
- Oracle Cursor (1)
- Oracle Database Appliance (1)
- Oracle Database Se2 (1)
- Oracle Database Standard Edition 2 (1)
- Oracle Database Upgrade (1)
- Oracle Database@Google Cloud (1)
- Oracle Exadata Smart Scan (1)
- Oracle Licensing (1)
- Oracle Linux Virtualization Manager (1)
- Oracle Oda (1)
- Oracle Openworld (1)
- Oracle Parallelism (1)
- Oracle RMAN (1)
- Oracle Rdbms (1)
- Oracle Real Application Clusters (1)
- Oracle Reports (1)
- Oracle Security (1)
- Oracle Wallet (1)
- Perfomrance (1)
- Performance Schema (1)
- Policy (1)
- Prompt Engineering (1)
- Public Cloud (1)
- Pythian News (1)
- Rdb (1)
- Replication Compatibility (1)
- Replication Error (1)
- Retail (1)
- Scaling Ir (1)
- Securing Sql Server (1)
- Security Compliance (1)
- Serverless Computing (1)
- Sso (1)
- Tenserflow (1)
- Teradata (1)
- Vertex AI (1)
- Vertica (1)
- Videos (1)
- Workspace Security (1)
- Xbstream (1)
- May 2025 (3)
- March 2025 (2)
- February 2025 (1)
- January 2025 (2)
- December 2024 (1)
- October 2024 (2)
- September 2024 (7)
- August 2024 (4)
- July 2024 (2)
- June 2024 (6)
- May 2024 (3)
- April 2024 (2)
- February 2024 (1)
- January 2024 (11)
- December 2023 (10)
- November 2023 (11)
- October 2023 (10)
- September 2023 (8)
- August 2023 (6)
- July 2023 (2)
- June 2023 (13)
- May 2023 (4)
- April 2023 (6)
- March 2023 (10)
- February 2023 (6)
- January 2023 (5)
- December 2022 (10)
- November 2022 (10)
- October 2022 (10)
- September 2022 (13)
- August 2022 (16)
- July 2022 (12)
- June 2022 (13)
- May 2022 (11)
- April 2022 (4)
- March 2022 (5)
- February 2022 (4)
- January 2022 (14)
- December 2021 (16)
- November 2021 (11)
- October 2021 (6)
- September 2021 (11)
- August 2021 (6)
- July 2021 (9)
- June 2021 (4)
- May 2021 (8)
- April 2021 (16)
- March 2021 (16)
- February 2021 (6)
- January 2021 (12)
- December 2020 (12)
- November 2020 (17)
- October 2020 (11)
- September 2020 (10)
- August 2020 (11)
- July 2020 (13)
- June 2020 (6)
- May 2020 (9)
- April 2020 (18)
- March 2020 (21)
- February 2020 (13)
- January 2020 (15)
- December 2019 (10)
- November 2019 (11)
- October 2019 (12)
- September 2019 (16)
- August 2019 (15)
- July 2019 (10)
- June 2019 (16)
- May 2019 (20)
- April 2019 (21)
- March 2019 (14)
- February 2019 (18)
- January 2019 (18)
- December 2018 (5)
- November 2018 (16)
- October 2018 (12)
- September 2018 (20)
- August 2018 (27)
- July 2018 (31)
- June 2018 (34)
- May 2018 (28)
- April 2018 (27)
- March 2018 (17)
- February 2018 (8)
- January 2018 (20)
- December 2017 (14)
- November 2017 (4)
- October 2017 (1)
- September 2017 (3)
- August 2017 (5)
- July 2017 (4)
- June 2017 (2)
- May 2017 (7)
- April 2017 (7)
- March 2017 (8)
- February 2017 (8)
- January 2017 (5)
- December 2016 (3)
- November 2016 (4)
- October 2016 (8)
- September 2016 (9)
- August 2016 (10)
- July 2016 (9)
- June 2016 (8)
- May 2016 (13)
- April 2016 (16)
- March 2016 (13)
- February 2016 (11)
- January 2016 (6)
- December 2015 (11)
- November 2015 (11)
- October 2015 (5)
- September 2015 (16)
- August 2015 (4)
- July 2015 (1)
- June 2015 (3)
- May 2015 (6)
- April 2015 (5)
- March 2015 (5)
- February 2015 (4)
- January 2015 (3)
- December 2014 (7)
- October 2014 (4)
- September 2014 (6)
- August 2014 (6)
- July 2014 (16)
- June 2014 (7)
- May 2014 (6)
- April 2014 (5)
- March 2014 (4)
- February 2014 (10)
- January 2014 (6)
- December 2013 (8)
- November 2013 (12)
- October 2013 (9)
- September 2013 (6)
- August 2013 (7)
- July 2013 (9)
- June 2013 (7)
- May 2013 (7)
- April 2013 (4)
- March 2013 (7)
- February 2013 (4)
- January 2013 (4)
- December 2012 (6)
- November 2012 (8)
- October 2012 (9)
- September 2012 (3)
- August 2012 (5)
- July 2012 (5)
- June 2012 (7)
- May 2012 (11)
- April 2012 (1)
- March 2012 (8)
- February 2012 (1)
- January 2012 (6)
- December 2011 (8)
- November 2011 (5)
- October 2011 (9)
- September 2011 (6)
- August 2011 (4)
- July 2011 (1)
- June 2011 (1)
- May 2011 (5)
- April 2011 (2)
- February 2011 (2)
- January 2011 (2)
- December 2010 (1)
- November 2010 (7)
- October 2010 (3)
- September 2010 (8)
- August 2010 (2)
- July 2010 (4)
- June 2010 (7)
- May 2010 (2)
- April 2010 (1)
- March 2010 (3)
- February 2010 (3)
- January 2010 (2)
- November 2009 (6)
- October 2009 (6)
- August 2009 (3)
- July 2009 (3)
- June 2009 (3)
- May 2009 (2)
- April 2009 (8)
- March 2009 (6)
- February 2009 (4)
- January 2009 (3)
- November 2008 (3)
- October 2008 (7)
- September 2008 (6)
- August 2008 (9)
- July 2008 (9)
- June 2008 (9)
- May 2008 (9)
- April 2008 (8)
- March 2008 (4)
- February 2008 (3)
- January 2008 (3)
- December 2007 (2)
- November 2007 (7)
- October 2007 (1)
- August 2007 (4)
- July 2007 (3)
- June 2007 (8)
- May 2007 (4)
- April 2007 (2)
- March 2007 (2)
- February 2007 (5)
- January 2007 (8)
- December 2006 (1)
- November 2006 (3)
- October 2006 (4)
- September 2006 (3)
- July 2006 (1)
- May 2006 (2)
- April 2006 (1)
- July 2005 (1)
No Comments Yet
Let us know what you think