Dremio is now part of SAP

Alex Merced

Head of DevRel, Dremio

Alex Merced is Head of DevRel for Dremio, a developer, and a seasoned instructor with a rich professional background. Having worked with companies like GenEd Systems, Crossfield Digital, CampusGuard, and General Assembly.

Alex is a co-author of the O’Reilly Book “Apache Iceberg: The Definitive Guide.”  With a deep understanding of the subject matter, Alex has shared his insights as a speaker at events including Data Day Texas, OSA Con, P99Conf and Data Council.

Driven by a profound passion for technology, Alex has been instrumental in disseminating his knowledge through various platforms. His tech content can be found in blogs, videos, and his podcasts, Datanation and Web Dev 101.

Moreover, Alex Merced has made contributions to the JavaScript and Python communities by developing a range of libraries. Notable examples include SencilloDB, CoquitoJS, and dremio-simple-query, among others.

Alex Merced's Articles and Resources

Apache Iceberg DML Support Matrix: MERGE, UPDATE, DELETE, and Branch Writes by EngineApache Iceberg DML Support Matrix: MERGE, UPDATE, DELETE, and Branch Writes by Engine

Blog Post

Apache Iceberg DML Support Matrix: MERGE, UPDATE, DELETE, and Branch Writes by Engine

Compare documented Iceberg MERGE, UPDATE, DELETE, overwrite, and branch-write support across Spark, Flink, Trino, and Dremio, with version caveats.

Read more ->
Incremental Processing with Apache Iceberg: Snapshot Scans, Changelog Views, and CheckpointsIncremental Processing with Apache Iceberg: Snapshot Scans, Changelog Views, and Checkpoints

Blog Post

Incremental Processing with Apache Iceberg: Snapshot Scans, Changelog Views, and Checkpoints

Build restartable Iceberg incremental pipelines with snapshot ranges, append scans, changelog views, durable checkpoints, branch awareness, and gap recovery.

Read more ->
Apache Iceberg Schema Evolution for Nested Data: Safe Changes and Compatibility RulesApache Iceberg Schema Evolution for Nested Data: Safe Changes and Compatibility Rules

Blog Post

Apache Iceberg Schema Evolution for Nested Data: Safe Changes and Compatibility Rules

Evolve nested Iceberg structs, lists, and maps safely using field IDs, nullability, type-promotion rules, defaults, and cross-engine compatibility tests.

Read more ->
Apache Iceberg Clustering and Sort Order Evolution: When to Rewrite DataApache Iceberg Clustering and Sort Order Evolution: When to Rewrite Data

Blog Post

Apache Iceberg Clustering and Sort Order Evolution: When to Rewrite Data

Evolve Iceberg sort orders safely, measure pruning quality, choose sort or Z-order rewrites, and decide when existing data justifies a controlled rewrite.

Read more ->
Apache Iceberg Write Distribution Modes: None, Hash, Range, and File SizingApache Iceberg Write Distribution Modes: None, Hash, Range, and File Sizing

Blog Post

Apache Iceberg Write Distribution Modes: None, Hash, Range, and File Sizing

Choose Iceberg write distribution mode none, hash, or range, then tune Spark adaptive execution and target file sizes for balanced, efficient writes.

Read more ->
Upgrading Apache Polaris in Production: Schema Migrations, Rolling Changes, and RollbackUpgrading Apache Polaris in Production: Schema Migrations, Rolling Changes, and Rollback

Blog Post

Upgrading Apache Polaris in Production: Schema Migrations, Rolling Changes, and Rollback

Upgrade Apache Polaris with compatibility checks, persistence schema migrations, rolling deployment gates, token tests, and a practical rollback plan.

Read more ->
Migrating from Nessie to Apache Polaris Without Rewriting Iceberg DataMigrating from Nessie to Apache Polaris Without Rewriting Iceberg Data

Blog Post

Migrating from Nessie to Apache Polaris Without Rewriting Iceberg Data

Plan a Nessie-to-Polaris Iceberg catalog migration that reuses existing object storage, validates table metadata, preserves rollback, and limits downtime.

Read more ->
Sizing Apache Polaris for Production: Load Testing, PostgreSQL Pools, and Helm ResourcesSizing Apache Polaris for Production: Load Testing, PostgreSQL Pools, and Helm Resources

Blog Post

Sizing Apache Polaris for Production: Load Testing, PostgreSQL Pools, and Helm Resources

Size Apache Polaris with workload-based load tests, PostgreSQL pool limits, Kubernetes requests and limits, replica scaling, and measurable capacity gates.

Read more ->
Apache Polaris Service Principals: Machine Identity, Secret Rotation, and Least PrivilegeApache Polaris Service Principals: Machine Identity, Secret Rotation, and Least Privilege

Blog Post

Apache Polaris Service Principals: Machine Identity, Secret Rotation, and Least Privilege

Design Apache Polaris service principals for machine workloads, rotate client secrets safely, assign least-privilege roles, and audit dormant identities.

Read more ->
Apache Polaris with Spark 4: REST Catalog, OAuth, and Credential VendingApache Polaris with Spark 4: REST Catalog, OAuth, and Credential Vending

Blog Post

Apache Polaris with Spark 4: REST Catalog, OAuth, and Credential Vending

Connect Spark 4 to Apache Polaris with the Iceberg REST catalog, OAuth credentials, catalog scopes, and storage credential vending, then verify writes.

Read more ->
Troubleshooting Apache Polaris REST API Authentication: 401, 403, Token, and Role ErrorsTroubleshooting Apache Polaris REST API Authentication: 401, 403, Token, and Role Errors

Blog Post

Troubleshooting Apache Polaris REST API Authentication: 401, 403, Token, and Role Errors

Diagnose Apache Polaris authentication failures by separating token issuance, validation, principal mapping, role grants, and credential-vending errors.

Read more ->
Observing Apache Polaris with Prometheus, OpenTelemetry, and JaegerObserving Apache Polaris with Prometheus, OpenTelemetry, and Jaeger

Blog Post

Observing Apache Polaris with Prometheus, OpenTelemetry, and Jaeger

Instrument Apache Polaris with Prometheus metrics, OpenTelemetry traces, Jaeger, request IDs, dashboards, alerts, and practical service-level objectives.

Read more ->
An Iceberg table carrying NDV, row count and column statistics, with Puffin metadata files holding column statistics, NDV sketches and histograms, feeding a query plan that scans, filters, joins, aggregates and projects.An Iceberg table carrying NDV, row count and column statistics, with Puffin metadata files holding column statistics, NDV sketches and histograms, feeding a query plan that scans, filters, joins, aggregates and projects.

Blog Post

Apache Iceberg Table Statistics: NDV, Puffin and Query Plans

Iceberg keeps per-file bounds automatically but table-level NDV statistics only when you compute them. Why that decides join order, and how to keep them fresh.

Read more ->
An unavailable Apache Polaris instance restored from backup storage holding snapshots and metadata. The recovered catalog holds tables, schemas and access policies, giving point in time recovery, data protection and business continuity.An unavailable Apache Polaris instance restored from backup storage holding snapshots and metadata. The recovered catalog holds tables, schemas and access policies, giving point in time recovery, data protection and business continuity.

Blog Post

Disaster Recovery for Apache Polaris: Backup and Restore

Recovering Polaris means recovering a metastore and object storage separately. What to back up, the order to restore in, and the failure mode nobody plans for.

Read more ->
Three clients each sending a commit to an Apache Iceberg table. Client B hits a conflict and is routed into a retry loop, while the table keeps each writer in its own isolated transaction.Three clients each sending a commit to an Apache Iceberg table. Client B hits a conflict and is routed into a retry loop, while the table keeps each writer in its own isolated transaction.

Blog Post

Apache Iceberg Concurrency: Commit Conflicts, Isolation and Retries

What causes an Iceberg commit conflict, the retry properties that govern it, the two isolation levels, and how to design conflicts out of a busy table.

Read more ->
Three file formats compared on a podium. Parquet is columnar, for analytics, with high compression. Avro is row oriented, for data exchange, with a flexible schema. ORC is columnar, high performance and optimised for Hadoop.Three file formats compared on a podium. Parquet is columnar, for analytics, with high compression. Avro is row oriented, for data exchange, with a flexible schema. ORC is columnar, high performance and optimised for Hadoop.

Blog Post

Parquet vs Avro vs ORC: Choosing a File Format in 2026

Parquet and ORC are columnar and built for reading. Avro is row-oriented and built for writing. How to choose, and why Iceberg quietly uses all three.

Read more ->
Apache Arrow shown as columnar data inside a processor chip and labelled in memory, columnar and built for fast analytics, beside Apache Parquet shown as files and a database and labelled on disk, a columnar file format optimised for storage.Apache Arrow shown as columnar data inside a processor chip and labelled in memory, columnar and built for fast analytics, beside Apache Parquet shown as files and a database and labelled on disk, a columnar file format optimised for storage.

Blog Post

Why Apache Arrow and Apache Parquet Are Not the Same Thing

Parquet is how columnar data sits on disk and Arrow is how it sits in memory. Every difference between them follows from that one split.

Read more ->
Apache Iceberg labelled a table format, its table holding snapshots, metadata and partitions and pointing to three data files, beside Apache Parquet labelled a file format and shown as four standalone Parquet files.Apache Iceberg labelled a table format, its table holding snapshots, metadata and partitions and pointing to three data files, beside Apache Parquet labelled a file format and shown as four standalone Parquet files.

Blog Post

Apache Iceberg vs Apache Parquet: Table Format or File Format?

Iceberg is a table format and Parquet is a file format. They are different layers of one stack, not alternatives, and an Iceberg table contains Parquet files.

Read more ->
Apache Iceberg 1.12.0 release guide covering v3 features, REST catalogs, Spark, Flink, and upgrade planningApache Iceberg 1.12.0 release guide covering v3 features, REST catalogs, Spark, Flink, and upgrade planning

Blog Post

Apache Iceberg 1.12.0: What’s New, Breaking Changes, and Upgrade Guide

Apache Iceberg 1.12.0 expands v3 engine support, REST catalog operations, streaming reliability, and v4 groundwork. Learn the breaking changes and use a practical upgrade plan.

Read more ->
Apache Polaris 1.8.0 release overview with authorization, pagination, database, command-line, and commit conflict conceptsApache Polaris 1.8.0 release overview with authorization, pagination, database, command-line, and commit conflict concepts

Blog Post

Apache Polaris 1.8.0: What’s New, Breaking Changes, and Upgrade Guide

Apache Polaris 1.8.0 adds semantic-model privileges, safer commit handling, pagination controls, CLI improvements, and important database upgrade steps.

Read more ->
Apache Iceberg Geospatial Types: Geometry and Geography in the LakehouseApache Iceberg Geospatial Types: Geometry and Geography in the Lakehouse

Blog Post

Apache Iceberg Geospatial Types: Geometry and Geography in the Lakehouse

Learn how Iceberg v3 stores geometry and geography, handles CRS metadata, writes Parquet values, and preserves spatial statistics across engines.

Read more ->
Apache Iceberg Views: Portable View Metadata Across SQL EnginesApache Iceberg Views: Portable View Metadata Across SQL Engines

Blog Post

Apache Iceberg Views: Portable View Metadata Across SQL Engines

See how the Iceberg View Spec stores SQL representations, schemas, dependencies, versions, and dialects so catalogs can share views across engines.

Read more ->
Apache Iceberg Table Encryption: KMS, Envelopes, and Parquet EncryptionApache Iceberg Table Encryption: KMS, Envelopes, and Parquet Encryption

Blog Post

Apache Iceberg Table Encryption: KMS, Envelopes, and Parquet Encryption

Understand Iceberg table encryption, envelope encryption, key metadata, KMS integration, Parquet modular encryption, and operational tradeoffs.

Read more ->
Server-Side Scan Planning in the Iceberg REST Catalog ExplainedServer-Side Scan Planning in the Iceberg REST Catalog Explained

Blog Post

Server-Side Scan Planning in the Iceberg REST Catalog Explained

Learn how Iceberg REST server-side scan planning works, including capabilities, asynchronous plans, polling, cancellation, batching, and tradeoffs.

Read more ->
Multi-Table Transactions with Iceberg REST Catalogs and Apache PolarisMulti-Table Transactions with Iceberg REST Catalogs and Apache Polaris

Blog Post

Multi-Table Transactions with Iceberg REST Catalogs and Apache Polaris

Explore Iceberg REST multi-table commit semantics, atomicity, conflict handling, client support, and the role of Apache Polaris in coordinated commits.

Read more ->
MERGE INTO Patterns for Apache Iceberg: Upserts and SCD Type 2MERGE INTO Patterns for Apache Iceberg: Upserts and SCD Type 2

Blog Post

MERGE INTO Patterns for Apache Iceberg: Upserts and SCD Type 2

Use MERGE INTO with Iceberg for idempotent upserts and SCD Type 2 history, with SQL patterns, deduplication, late data, and file maintenance.

Read more ->
Apache Iceberg Storage Costs: Requests, Retention, and Lifecycle RulesApache Iceberg Storage Costs: Requests, Retention, and Lifecycle Rules

Blog Post

Apache Iceberg Storage Costs: Requests, Retention, and Lifecycle Rules

Model Iceberg storage cost across bytes, object requests, snapshots, metadata, compaction, and lifecycle rules without breaking table history.

Read more ->
Monitoring Iceberg Table Health with Metrics Reports and Metadata TablesMonitoring Iceberg Table Health with Metrics Reports and Metadata Tables

Blog Post

Monitoring Iceberg Table Health with Metrics Reports and Metadata Tables

Build Iceberg observability with ScanReport, CommitReport, REST metrics, metadata-table queries, SLOs, alerts, and a practical health dashboard.

Read more ->
Apache Polaris Realms: Multi-Tenancy and Tenant IsolationApache Polaris Realms: Multi-Tenancy and Tenant Isolation

Blog Post

Apache Polaris Realms: Multi-Tenancy and Tenant Isolation

Learn how Polaris realms partition identities and metadata for multi-tenant deployments, what they isolate, and which controls still belong outside Polaris.

Read more ->
Apache Polaris with OIDC: Keycloak, Okta, and External Identity ProvidersApache Polaris with OIDC: Keycloak, Okta, and External Identity Providers

Blog Post

Apache Polaris with OIDC: Keycloak, Okta, and External Identity Providers

Configure Apache Polaris with an external OIDC provider, map claims to principals and roles, rotate keys, and troubleshoot Keycloak or Okta authentication.

Read more ->
get started

Get Started Free

No time limit - totally free - just the way you like it.

Sign Up Now
demo on demand

See Dremio in Action

Not ready to get started today? See the platform in action.

Watch Demo
talk expert

Talk to an Expert

Not sure where to start? Get your questions answered fast.

Contact Us

Make data engineers and analysts 10x more productive

Boost efficiency with AI-powered agents, faster coding for engineers, instant insights for analysts.