--- title: DumboDB: Announcing Validator Support | daily.dev description: DumboDB, DoltHub's version-controlled MongoDB clone, has added support for schema validators. The post reviews how MongoDB-style $jsonSchema validators,... canonical: https://daily.dev/posts/dumbodb-announcing-validator-support-pxoap3acs twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: DumboDB: Announcing Validator Support | daily.dev og:description: DumboDB, DoltHub's version-controlled MongoDB clone, has added support for schema validators. The post reviews how MongoDB-style $jsonSchema validators,... og:url: https://daily.dev/posts/dumbodb-announcing-validator-support-pxoap3acs og:image: https://api.daily.dev/og/posts/PxoAp3aCS.png og:image:alt: DumboDB: Announcing Validator Support og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # DumboDB: Announcing Validator Support **[DoltHub Blog](https://daily.dev/sources/dolthub-blog)** · 15 min read · 12 upvotes · 0 comments ## Summary DumboDB, DoltHub's version-controlled MongoDB clone, has added support for schema validators. The post reviews how MongoDB-style $jsonSchema validators, validationLevel, and validationAction work, then explains the complications version control introduces: validators and data can diverge across branches, leading to validator conflicts and document validation conflicts during merges. It walks through a full example using dumboDiff, dumboConflicts, and dumboResolveConflict to perform a two-phase conflict resolution (resolve the validator conflict first, then fix documents that fail the newly merged validator) before completing a merge. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How does DumboDB handle merge conflicts when validators differ between branches? DumboDB uses a two-phase conflict resolution process. First it merges the validator definitions themselves, requiring dumboResolveConflict to resolve any conflicting $jsonSchema rules between branches. Second, once validators are merged, it checks all altered documents in the incoming branch against the new validator and surfaces any document-level validation conflicts, which must also be resolved with dumboResolveConflict before the merge can complete. _Teams merging branches with divergent schema rules can track database version control changes like this via daily.dev._ ### What do MongoDB's validationLevel and validationAction options control when validating documents against a $jsonSchema? validationLevel controls which documents are checked during writes: strict applies rules to all inserts and updates, moderate only enforces rules on updates to documents that already satisfy the validator, and off disables enforcement while keeping the schema stored. validationAction controls what happens on failure: error rejects the write, while warn logs a warning but lets the write succeed, useful during migrations. _Developers tuning schema enforcement strategy can follow database validation changes on daily.dev._ ### Does updating a MongoDB collection's validator with collMod retroactively validate existing documents? No, validator rules only apply at the time a document is inserted or updated. Creating a collection without validators, adding documents, then applying stricter validators with collMod leaves existing documents untouched even if they no longer satisfy the schema; these grandfathered documents remain in the database until explicitly fixed, and can be located with a $nor query against the $jsonSchema. _Anyone migrating schema rules in production can keep up with database validation nuances on daily.dev._ ## Similar posts on daily.dev - [DumboDB Indexes: They Work Now\!](https://daily.dev/posts/dumbodb-indexes-they-work-now--xwxczewbi) · DoltHub Blog · 5 upvotes · 0 comments - [DumboDB Supports MongoDB Compass](https://daily.dev/posts/dumbodb-supports-mongodb-compass-yw7xn2huo) · DoltHub Blog · 1 upvotes · 0 comments - [DumboDB: Introducing Merge Modes](https://daily.dev/posts/dumbodb-introducing-merge-modes-7ojjfquhx) · DoltHub Blog · 2 upvotes · 0 comments - [Stop fighting forms: The schema-driven approach to validation](https://daily.dev/posts/stop-fighting-forms-the-schema-driven-approach-to-validation-8vq511w0o) · LogRocket · 1 upvotes · 0 comments - [DumboDB: Announcing Replication V1](https://daily.dev/posts/dumbodb-announcing-replication-v1-gsfb5lcot) · DoltHub Blog · 4 upvotes · 0 comments --- Tags: [#mongodb](https://daily.dev/tags/mongodb), [#version-control](https://daily.dev/tags/version-control) [View this post on daily.dev](https://daily.dev/posts/dumbodb-announcing-validator-support-pxoap3acs) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"DumboDB: Announcing Validator Support","url":"https://daily.dev/posts/dumbodb-announcing-validator-support-pxoap3acs","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/dumbodb-announcing-validator-support-pxoap3acs"},"datePublished":"2026-08-18T23:58:43.704Z","dateModified":"2026-09-13T21:47:09.807Z","description":"DumboDB, DoltHub's version-controlled MongoDB clone, has added support for schema validators. The post reviews how MongoDB-style $jsonSchema validators,...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/2a8371d4eef34b31dee0b7c247953d6f?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/2a8371d4eef34b31dee0b7c247953d6f?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"DoltHub Blog","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"DoltHub Blog","logo":"https://media.daily.dev/image/upload/s--LXDlvjS4--/f_auto,q_auto/v1780213587/logos/dolthub-blog?_a=BAMAMiWQ0","url":"https://daily.dev/sources/dolthub-blog"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/dumbodb-announcing-validator-support-pxoap3acs","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":12},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"mongodb,version-control","timeRequired":"PT15M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"DoltHub Blog","item":"https://daily.dev/sources/dolthub-blog"},{"@type":"ListItem","position":3,"name":"DumboDB: Announcing Validator Support"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/dumbodb-announcing-validator-support-pxoap3acs#faq","mainEntity":[{"@type":"Question","name":"How does DumboDB handle merge conflicts when validators differ between branches?","acceptedAnswer":{"@type":"Answer","text":"DumboDB uses a two-phase conflict resolution process. First it merges the validator definitions themselves, requiring dumboResolveConflict to resolve any conflicting $jsonSchema rules between branches. Second, once validators are merged, it checks all altered documents in the incoming branch against the new validator and surfaces any document-level validation conflicts, which must also be resolved with dumboResolveConflict before the merge can complete. Teams merging branches with divergent schema rules can track database version control changes like this via daily.dev."}},{"@type":"Question","name":"What do MongoDB's validationLevel and validationAction options control when validating documents against a $jsonSchema?","acceptedAnswer":{"@type":"Answer","text":"validationLevel controls which documents are checked during writes: strict applies rules to all inserts and updates, moderate only enforces rules on updates to documents that already satisfy the validator, and off disables enforcement while keeping the schema stored. validationAction controls what happens on failure: error rejects the write, while warn logs a warning but lets the write succeed, useful during migrations. Developers tuning schema enforcement strategy can follow database validation changes on daily.dev."}},{"@type":"Question","name":"Does updating a MongoDB collection's validator with collMod retroactively validate existing documents?","acceptedAnswer":{"@type":"Answer","text":"No, validator rules only apply at the time a document is inserted or updated. Creating a collection without validators, adding documents, then applying stricter validators with collMod leaves existing documents untouched even if they no longer satisfy the schema; these grandfathered documents remain in the database until explicitly fixed, and can be located with a $nor query against the $jsonSchema. Anyone migrating schema rules in production can keep up with database validation nuances on daily.dev."}}]} ```