Semantic Types

Choose a column type and check which inputs it accepts.

A semantic type tells Silo how to check a value and store it in SQLite. For example, text/datetime accepts a timestamp with a time zone and converts it to UTC. text/enum accepts only the strings listed in the column definition.

Each type uses one SQLite storage class: TEXT, INTEGER, REAL, BLOB, or ANY. Some types also add SQLite constraints or format values for row output.

Use this page to choose a type or understand a rejected value. Column examples below belong in a table definition's columns array. See Design a schema for a complete table.

Use the column comment to explain what the value means. For example, say which currency an amount uses and whether null means “unknown” or “not applicable.”

Choose a type quickly

Value you need	Type to consider
Unstructured text	text
Native JSON object or array	text/json
Timestamp with a time zone	text/datetime
Calendar date	text/date
UUID or ULID identity	text/uuid or text/ulid
Exact amount	integer/money-minor or configured text/decimal
Boolean flag	integer/boolean
Fraction from 0 to 1	real/percentage
Arbitrary SQLite scalar	any

Null, defaults, and canonical values

JSON null becomes SQL NULL only when the column is nullable. Non-nullable columns reject it. Literal defaults go through the same checks and conversion as values in a write request.

For example, this default is stored as a UTC instant rather than preserving its input offset:

{
  "name": "observed_at",
  "type": "text/datetime",
  "nullable": false,
  "default": { "literal": "2026-07-11T09:30:00-04:00" },
  "comment": "UTC instant represented by this observation."
}

The example default becomes 2026-07-11T13:30:00.000Z.

Base storage types

Type	Accepted JSON value	Stored behavior
text	String	Stores the string unchanged.
integer	Safe integer	Stores the integer unchanged.
real	Finite number	Stores the number unchanged.
blob	Base64 string	Decodes and stores bytes.
any	String, finite number, boolean, or nullable null	Stores a SQLite scalar; booleans become 0 or 1. Objects and arrays are rejected.

Text types

Type	Accepted form	Normalization or options
text/uuid	UUID with a version digit from 1 through 8 and RFC variant bits	Lowercase.
text/ulid	26-character ULID	Uppercase.
text/slug	Lowercase letters and digits separated by single hyphens	None.
text/git-oid	Hexadecimal object ID	Lowercase; set type_options.length explicitly to 40 or 64.
text/date	Valid YYYY-MM-DD calendar date	Rejects rollover dates such as 2025-02-30.
text/time	HH:MM:SS, optional fractional seconds, optional Z or numeric offset	None.
text/datetime	ISO-like instant with Z or numeric offset	Converts to a UTC ISO string.
text/json	JSON object, array, string, finite number, or boolean	Stores compact JSON text.
text/markdown	String	No content transformation.
text/html	String	No content transformation.
text/url	URL with a protocol and hostname	None.
text/uri	String beginning with a URI scheme	None.
text/email	Basic local-part, @, and dotted-domain form	None.
text/ip	IPv4 or IPv6 address	None.
text/cidr	IP address plus valid prefix length	None.
text/hostname	DNS-style hostname up to 253 characters	Lowercase.
text/path	String without a null byte	Platform-neutral validation only.
text/path-posix	String without a null byte or backslash	None.
text/path-relative	String that does not start with / or contain a slash-separated .. segment	None.
text/git-ref	String excluding Git's forbidden ref patterns	None.
text/semver	Semantic version with optional prerelease and build suffixes	None.
text/base64	Valid padded base64 text	Stores text rather than decoded bytes.
text/hex	Even-length hexadecimal text	Lowercase.
text/sha256	64 hexadecimal characters	Lowercase.
text/sha512	128 hexadecimal characters	Lowercase.
text/decimal	Signed decimal string without exponent notation	Requires integer precision and scale; pads fractional digits to scale.
text/enum	One configured string	Requires type_options.values.

Git object IDs

Set type_options.length explicitly for text/git-oid. The current default validator rejects ordinary Git hashes when the option is omitted.

For a SHA-1 repository, this column accepts a 40-character hexadecimal ID and stores it in lowercase:

{
  "name": "commit_id",
  "type": "text/git-oid",
  "type_options": { "length": 40 },
  "nullable": false,
  "comment": "Git commit containing the change."
}

Use 64 for a SHA-256 repository.

Exact decimals

Configure an exact decimal with six total digits and two fractional digits:

{
  "name": "amount",
  "type": "text/decimal",
  "type_options": { "precision": 6, "scale": 2 },
  "nullable": false,
  "comment": "Exact transaction amount in account currency."
}

An input of "12.5" is stored as "12.50"; exponent notation and values exceeding the configured precision or scale are rejected.

Allowed strings

Use an enum when only a known set of strings is valid:

{
  "name": "state",
  "type": "text/enum",
  "type_options": { "values": ["open", "closed"] },
  "nullable": false,
  "comment": "Whether the issue still needs work."
}

The column accepts "open" and "closed". It rejects other strings and null.

Integer, real, and blob types

Type	Accepted form	Additional behavior
integer/boolean	JSON boolean or integer 0 or 1	Stores 0 or 1; row output renders a boolean.
integer/positive	Safe integer greater than zero	Adds a physical check.
integer/nonnegative	Safe integer zero or greater	Adds a physical check.
integer/port	Safe integer from 0 through 65535	Adds a physical check.
integer/unix-seconds	Safe integer	Unit meaning is documented, not range-limited.
integer/unix-milliseconds	Safe integer	Unit meaning is documented, not range-limited.
integer/duration-ms	Nonnegative safe integer	Adds a physical check.
integer/money-minor	Safe integer	Unit meaning is documented by the column comment.
real/percentage	Finite number from 0 through 1	Adds a physical check.
blob/bytes	Base64 JSON string	Decodes and stores bytes.

real/percentage uses fractions: 0.25 means 25%; 25 is rejected. For integer/money-minor, document the unit, such as cents, in the column comment. The type does not choose a currency for you.

Text validation checks form, not whether a resource exists or is safe to use. For example, text/url does not fetch the URL, and text/path-relative does not make a path safe for every operating system. text/html stores its input without sanitizing it.