docs: Add HTTL command reference page

[Copilot]

Adds documentation for HTTL, a read-only command that returns the remaining TTL in seconds for individual fields within a hash — filling a gap where only key-level TTL existed before.

Changes

• docs/command-reference/hashes/httl.md — New command reference covering:
  • Syntax: HTTL key FIELDS numfields field [field ...]
  • Return semantics: -2 (field/key missing), -1 (no expiry), positive int (remaining TTL)
  • Examples: fields with/without expiry, non-existent key, wrong type error
  • Notes on read-only behavior and relation to HEXPIRE/HSETEX
  • Links to related hash TTL commands

Example

dragonfly> HSET myhash field1 "hello" field2 "world"
(integer) 2
dragonfly> HEXPIRE myhash 30 FIELDS 1 field1
1) (integer) 1
dragonfly> HTTL myhash FIELDS 3 field1 field2 nosuchfield
1) (integer) 29
2) (integer) -1
3) (integer) -2

Original prompt

Add a new documentation page describing the HTTL command, introduced in dragonflydb/dragonfly PR #6879 (dragonflydb/dragonfly#6879). This command allows querying the TTL (Time-To-Live) of individual fields within Redis hash objects. The documentation must include:

• A clear explanation of what HTTL does and when developers might need it.
• Syntax, usage examples (with inputs/outputs) and a breakdown of parameters.
• Comparison to existing Redis TTL commands and explanation of how HTTL addresses hash limitations.
• Edge case handling, including usage with non-existent hashes or fields.
• Version and compatibility details (when it landed, whether it's unique to Dragonfly, etc.).
• Performance and practical implications (bulk queries, scripting, latency).
• Links to related documentation or blog posts.

Style must be consistent with the rest of the documentation: clear, objective, with signposting and progressive disclosure, and accessible for both junior and senior developers. Begin with a concise summary that motivates use of HTTL for granular cache management. End with key takeaways and cross-references to broader TTL concepts.

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: @dragonflydb/dragonfly/pull/6879
add documentation page based on the attached PR into https://github.com/dragonflydb/documentation/

Assistant: Absolutely — great idea.

I can help draft the docs content, but to actually add it into dragonflydb/documentation I’ll need to open a PR there.

If you want me to do that now, please confirm and I’ll create a PR in:

• dragonflydb/documentation

based on:

• https://github.com/dragonflydb/dragonfly/pull/6879 (“Add HTTL command for hash field TTL queries”)

I can include:
1.

User: @dragonflydb/dragonfly/pull/6879
add documentation page based on the attached PR into https://github.com/dragonflydb/documentation/

Assistant: I'm preparing a documentation page for the HTTL command as introduced in PR #6879, which will be added to https://github.com/dragonflydb/documentation/.

Once the PR is ready, I'll present a draft of the documentation for your review, covering usage, syntax, comparisons, edge cases, and more, as specified.

This pull request was created from Copilot chat.

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Project	Deployment	Actions	Updated (UTC)
documentation	Ready	Preview, Comment	Mar 15, 2026 10:04pm

[kostasrim]

lgtm