URLNotesGrabberCore/URLNotesGrabberCORE/TL.db.md

TL.db — schema notes

The SQLite database behind URLNotesGrabberCORE and its sibling crawlers, and the one Rolodex reads.

Everything below was read out of the live file, not inferred from code. Counts are as of 2026-07-29; re-run the queries at the bottom to refresh them.

• Journal mode: WAL — TL.db-wal and TL.db-shm live beside the file and are part of the database. Copying TL.db alone gives you whatever was last checkpointed, not the current state.
• Page size: 4096.

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The three content tables

Table	Rows	What it is
Blogs	144,367	The crawl registry — one row per known blog, plus crawl-state flags
Posts	14,589	Stored post content. Only 3,602 blogs actually have any
Notes	1,189,604	The engagement graph: NoteBlogName acted on (RootBlogName, PostID)

The engagement graph is the interesting part. 31,888 distinct blogs appear as engagers — far more than the 3,602 that have stored posts — which is what makes this a social graph rather than a post archive.

Blogs

CREATE TABLE "Blogs" (
    "BlogName"              TEXT,
    "HasBeenOutput"         INTEGER DEFAULT 0,
    "IsActive"              INTEGER DEFAULT 1,
    "DateAdded"             TEXT NOT NULL DEFAULT '12/24/25',
    "ByLikes"               INTEGER NOT NULL DEFAULT 0,
    "LikesPulled"           INTEGER NOT NULL DEFAULT 0,
    "LikesCursor"           INTEGER DEFAULT 0,
    "DateModified"          TEXT,
    "DateCreated"           TEXT,
    LikesNewestTimestamp    INTEGER DEFAULT 0,
    LikesLastRefreshed      INTEGER DEFAULT 0,
    LikesLastNewCount       INTEGER DEFAULT 0,
    TTFolderPath            TEXT,
    PRIMARY KEY("BlogName")
);

BlogName is the primary key, so it is the only indexed way in. There is no index on any flag or date — filtering or sorting on those scans all 144k rows, which is affordable here and is not on Notes.

Flag distribution: IsActive = 1 on 144,366 of 144,367 rows, HasBeenOutput = 1 on 5,369, ByLikes = 1 on 2. IsActive carries a second meaning as of Rolodex — see Blogs.IsActive below.

The columns after DateCreated were added later by ALTER TABLE, which is why they carry no quoting in the stored DDL. That is the normal way this schema grows.

DateAdded is not written consistently. 126,423 rows hold ISO yyyy-MM-dd HH:mm:ss; 17,944 hold US-format M/d/yy from a bulk import. As text those two sort into different parts of the table, so anything ordering or range-filtering on this column has to normalise first — see DateSql in Rolodex.

Posts

CREATE TABLE "Posts" (
    "BlogName"              TEXT,
    "PostID"                INTEGER,
    "HasNotesGathered"      INTEGER DEFAULT 0,
    "reblogURL"             TEXT,
    "NotFound"              INTEGER DEFAULT 0,
    "PostDate"              TEXT,
    "NotesGatheredDateTime" INTEGER NOT NULL DEFAULT 1729746000,
    "HasImage"              INTEGER NOT NULL DEFAULT 0,
    "PostURL"               TEXT,
    "Slug"                  TEXT,
    "ReblogKey"             TEXT,
    "ReblogName"            TEXT,
    "Summary"               TEXT,
    "Quote"                 TEXT,
    "Body"                  TEXT,
    "Tags"                  TEXT,
    "Link"                  TEXT,
    "PhotoURL"              TEXT,
    "PhotoCaption"          TEXT,
    "DownloadedFiles"       TEXT,
    "AudioCaption"          TEXT,
    "Question"              TEXT,
    "Answer"                TEXT,
    "Title"                 TEXT,
    "ByLikes"               INTEGER NOT NULL DEFAULT 0,
    "RootBlogName"          TEXT,
    "RootURL"               TEXT,
    "DateModified"          TEXT,
    "DateCreated"           TEXT,
    PostType                TEXT,
    PRIMARY KEY("BlogName","PostID")
);

The key is (BlogName, PostID), not PostID. This matters more than it looks: 325 post IDs exist under more than one blog, so an ID on its own is both ambiguous and unindexed. Any lookup should carry the blog name, and a batch lookup should group by blog so it stays on the leading column of the key.

Notable:

• PostType is NULL on all 14,589 rows. The column exists but nothing has ever populated it. Treat it as unpopulated rather than as a type discriminator.
• HasImage = 1 on 14,268 rows — nearly all of them. It records that the post had a picture, not that a usable URL was kept, so it is not a reliable predictor that anything will render.
• PhotoURL is largely unused; in practice the image markup lives inside Body.
• NotFound = 1 on 4,663 rows — posts that have since been deleted upstream.
• The content columns (Body, Quote, Question, Answer, …) are the heavy ones. List views should not select them.

Notes

CREATE TABLE "Notes" (
    "RootBlogName"      TEXT,
    "PostID"            INTEGER,
    "NoteBlogName"      TEXT,
    "TimeStamp"         INTEGER,
    "Type"              TEXT,
    "replyText"         TEXT DEFAULT '.',
    "DatetimeCrawled"   TEXT DEFAULT '2/12/26 12am',
    "DateModified"      TEXT,
    "DateCreated"       TEXT,
    IsActive            INTEGER NOT NULL DEFAULT 1,
    PRIMARY KEY("RootBlogName","PostID","TimeStamp","Type","NoteBlogName")
) WITHOUT ROWID;

CREATE INDEX "ix_NoteBlogName01" ON "Notes" ("NoteBlogName");

WITHOUT ROWID, since 2026-08-07. The rows live in the primary key's b-tree rather than in a rowid table with a separate key index beside it. Nothing about the SQL surface changes — same columns, same types, same constraint — but two consequences are worth knowing before adding an index here:

• There is no rowid on this table. SELECT rowid FROM Notes is an error, and no code in any of the three apps relied on it.
• A secondary index carries the whole five-column primary key as its row reference instead of a compact rowid, so indexes on this table are expensive. ix_NoteBlogName01 costs 58 MB, up from 25 MB before the conversion. It earns that: Rolodex filters on NoteBlogName and the crawler joins on it.

Notes_idx_06e01ae3 on TimeStamp DESC was dropped at the same time. It cost 14 MB as a rowid index and would have cost 58 MB after the conversion. It was worth neither: the crawler's only TimeStamp filter (>= 1535778000) excludes 786 rows of 1.18M, Rolodex's default Notes sort carries a three-column tiebreaker that forces a full sort regardless, and the reply-matching UPDATE uses ABS(TimeStamp - ?) <= 5, which no index on TimeStamp can serve. The one path that got slower is Rolodex's Notes page with a date-range filter: 60 ms to 164 ms.

See ../shrink-db.sql for the full rationale and the applied result.

DatetimeCrawled is NULL on 1,148,077 rows, and that is the honest value. Those rows previously stored the literal string '2/12/26 12am' — this column's own DDL default, written as a bulk backfill placeholder rather than as a crawl time. They were set to NULL on 2026-08-07, which is what consumers already displayed them as: the string parses as a date in neither format this schema writes.

Note the trap: the DEFAULT '2/12/26 12am' clause is still in the DDL above. Any INSERT that omits this column writes the placeholder straight back. The crawler names it explicitly on every insert, so nothing reintroduces it today, but a new writer that forgets to would — which is why consumers should keep treating an unparseable value here as "unknown" rather than assuming NULL is now the only such marker.

One row per engagement event. TimeStamp is unix seconds — unlike every date column elsewhere in the schema, which are text.

Type	Rows	Share
like	947,955	79.7%
reblog	224,323	18.9%
reply	15,201	1.3%
posted	2,106	0.2%
post_attribution	19	—

At 1.19M rows this is the table that dictates how the whole database has to be queried:

• Nothing should run an unbounded SELECT or a bare COUNT(*) here. A count scans the lot on every call.
• The only fast access paths are the primary key's leading columns (RootBlogName, then PostID) and ix_NoteBlogName01 on NoteBlogName. "Notes received by a blog" and "notes given by a blog" are both cheap; almost nothing else is.
• Every ordering here is a full sort of whatever the filters leave, TimeStamp included. That was already true in practice of the default TimeStamp order, whose tiebreakers forced a sort even while Notes_idx_06e01ae3 existed; since that index was dropped on 2026-08-07 it is true unconditionally. Filter first, then sort.
• replyText is '.' on 1,167,464 rows — only reply notes carry real text.

Referential integrity

There are no foreign keys, and the tables do not perfectly agree:

• 4 Posts rows name a blog with no Blogs row.
• 15 of the 31,888 distinct engagers have no Blogs row.

So a name appearing in Notes or Posts is not a guarantee that the registry knows about it. Joins from those tables back to Blogs should tolerate a miss.

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The '.' placeholder convention

The crawler writes a single dot into text columns it has no value for, rather than NULL. This is the single most surprising thing about the schema and it affects every consumer.

Column	'.' rows
Notes.replyText	1,167,464
Posts.Title	13,144
Posts.Body	172

Any query whose output reaches a human should collapse it:

NULLIF(NULLIF(SomeColumn, '.'), '') AS SomeColumn

Empty string turns up too, hence the double NULLIF. Not every column is affected — Blogs.TTFolderPath and Blogs.DateModified currently have zero dot rows — but new columns tend to acquire them, so treat cleaning as the default for any text column rendered to a user.

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Supporting tables

Crawler bookkeeping. Rolodex ignores all of these.

Table	Rows	What it is
DailyAPICount	133	(Date TEXT PK, APICount INTEGER) — per-day API call tally against the rate limit
ApiKeyPoolState	2	(KeyName TEXT PK, RetryUntil INTEGER) — per-key backoff; RetryUntil is unix seconds
ApiKeyPoolMeta	1	(Id PK CHECK (Id = 1), LastIndex) — round-robin cursor. Singleton by check constraint
CollectRunState	1	(Id PK CHECK (Id = 1), RunCutoff, RunComplete, RunStarted, RunCompletedAt) — resume state for an interrupted collection run. Also a singleton

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Blogs.IsActive — now written by two applications

IsActive has always been the crawler's work-selection flag. GetBlogs in DataAccess.cs joins on it to decide what to collect:

SELECT NoteBlogName, count(*) FROM notes
INNER JOIN blogs ON blogs.BlogName = notes.NoteBlogName
WHERE blogs.IsActive = @isActive AND ...

Nothing inside the crawler writes it — it is an input, set from outside.

Rolodex is now one of the things that sets it. Removing a blog through the Rolodex UI runs exactly this:

UPDATE Blogs SET IsActive = 0 WHERE BlogName = ?;

Rolodex adds no column and changes no schema. It reuses this flag because the two meanings were judged to be one decision: a blog you do not want in the browsing UI is a blog you do not want to keep crawling. Removal therefore stops collection, and the Rolodex confirmation screen says so before anyone commits.

• 1 (or absent/NULL) — live. Crawled, and visible in Rolodex.
• 0 — removed. Not crawled, hidden from the Rolodex registry, dashboard counts and engagement rollups.

Restoring is the same UPDATE with a 1. Nothing is destroyed either way: the blog's Posts and Notes rows are never touched, and Rolodex deliberately keeps showing them under its Posts and Notes pages. Removing a blog hides the blog, not what it collected.

What other tools need to know

1. Setting IsActive = 0 now also hides the blog from Rolodex, and setting it back to 1 makes it reappear. If another tool deactivates blogs in bulk, it is also removing them from the browsing UI — which may be exactly right, but it is no longer a crawler-only decision.
2. Re-crawling a removed blog will not bring it back, since nothing in the crawler writes the flag. An INSERT OR REPLACE on the Blogs row would, by resetting it to the column default of 1. Prefer an UPDATE of the specific columns, or INSERT … ON CONFLICT DO UPDATE SET naming only the columns being refreshed.
3. NULL is treated as live. The column is INTEGER DEFAULT 1 with no NOT NULL, so Rolodex reads it through COALESCE(IsActive, 1). A NULL therefore leaves the blog visible rather than stranding it outside both the registry and the removed list, where no screen could reach it. Write 0 or 1, not NULL.
4. Backing the feature out is a configuration change, not a migration. Because there is no Rolodex-owned column, setting Rolodex__EnableBlogDeletion=false is the whole of it; there is nothing to drop. Any blogs already at IsActive = 0 simply go back to being ordinary inactive blogs.

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Posts.IsActive and Notes.IsActive — optional, and not in this database yet

The same flag is being extended to the two content tables, with the same meaning: 0 is removed, anything else — including NULL — is live. Neither column exists in the live TL.db as of 2026-07-29; the DDL quoted above for Posts and Notes is complete. Like Blogs.IsActive, they are written from outside this crawler.

The crawler therefore treats both as optional, and as nothing it owns:

• It never writes them. No INSERT column list names IsActive, no UPDATE sets it, and MapPrefixToColumn — the only place a column name is chosen at runtime — cannot map to it. Re-crawling a removed post or note refreshes its content and leaves the flag at 0. There is no INSERT OR REPLACE on Posts or Notes for a default to be reset by.
• It filters on them only when they exist. HasIsActiveColumn in DataAccess.cs asks PRAGMA table_info once per table per database path and caches the answer; the filter is COALESCE(IsActive, 1) = 1, and it is dropped entirely when the column is absent. Naming a missing column is a hard SQLite error, so this is what lets one build run against databases on both sides of the change. The cache lives for the process — adding the columns to a live database takes effect on the next run.

Every read that selects posts or notes carries the filter: GetPosts, GetReplies, GetRepliesWithMissingText, GetRepliesWithFilledText, GetAllPostTextColumns, GetAllPostsForBlog, GetPost, GetPostByIdAnyBlog, and the engagement queries that count or join Notes (GetBlogs, GetBlogsAll, GetBlogsForLikes). The one deliberate omission is the LEFT JOIN Notes in GetPosts: nothing is selected from it and it can neither add nor remove a row, so filtering it would buy nothing.

LegacyPostsDbImporter is unfiltered too — it reads a foreign legacy database whose Posts table is not this schema.

Two consequences worth stating plainly, both inherited from how Blogs.IsActive is handled:

1. Removal hides a row; it does not freeze it. The write paths are keyed on a post the caller already selected, so an ingest or a correction run still overwrites the content of a removed post. Only selection is filtered.
2. NULL is live. Write 0 or 1, not NULL, but a NULL leaves the row visible rather than stranding it.

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Reproducing the numbers

SELECT 'Blogs', COUNT(*) FROM Blogs
UNION ALL SELECT 'Posts', COUNT(*) FROM Posts
UNION ALL SELECT 'Notes', COUNT(*) FROM Notes;

-- note type mix
SELECT Type, COUNT(*) FROM Notes GROUP BY Type ORDER BY 2 DESC;

-- the two date shapes in Blogs.DateAdded
SELECT CASE WHEN DateAdded LIKE '____-__-__%' THEN 'ISO' ELSE 'US' END, COUNT(*)
FROM Blogs GROUP BY 1;

-- post IDs that are ambiguous without a blog name
SELECT COUNT(*) FROM (
    SELECT PostID FROM Posts GROUP BY PostID HAVING COUNT(DISTINCT BlogName) > 1);

-- rows that reference a blog the registry does not have
SELECT COUNT(*) FROM Posts p
WHERE NOT EXISTS (SELECT 1 FROM Blogs b WHERE b.BlogName = p.BlogName);

Open the file read-only so an inspection can never disturb a running crawl:

sqlite3 "file:TL.db?mode=ro" ".schema"