Feature dbwrite

.gitignore

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 *.swp
+di/dbwrite/sortconfig.csv

di/dbwrite/dbwrite.md

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+# di.dbwrite
+
+Write, sort, and attribute utilities for kdb+ processes that persist data to disk (rdb, wdb, tickerlogreplay).
+
+A **config table** (`tabname`,`att`,`column`,`sort`) drives which columns are sorted and which attributes are applied per table. Load it once with `readcsv` (from a CSV) or `setconfig` (from an in-memory table); `sort` and `savedown` read from module state automatically. A table with no explicit entry falls back to a `default` row; if no config has been loaded, the built-in default (sort every table by `time` ascending) applies.
+
+---
+
+## Features
+
+- Write an in-memory table to a date-partitioned HDB with `savedown` — enumerates syms, writes, sorts per stored config, then runs `.Q.gc[]`
+- Append rows to an existing partition with `appenddown` — enumerates syms and appends; sort separately when the partition is complete
+- Sort on-disk table partitions by configured columns using `xasc`, then apply kdb+ attributes (`p`,`s`,`g`,`u`)
+- Config loaded once via `readcsv` (from a CSV) or `setconfig` (from a table); inspectable at any time with `getconfig`
+- Sort and attribute errors are caught-and-logged (a single partition failure does not halt the run); config and write errors are raised to the caller with a `di.dbwrite:` prefix
+
+---
+
+## Dependencies
+
+| Dependency | Key | Required | Description |
+|---|---|---|---|
+| logger | `` `log `` | yes | Functions `info`,`warn`,`error` — each monadic `{[msg] ...}` |
+
+The `log` dependency must be passed to `init`. The module throws if it is absent, `(::)`, or missing any of the three keys. The functions are monadic message loggers (`{[msg] ...}`); a [`kx.log`](https://github.com/KxSystems/logging) instance satisfies the contract. The module folds its own context into each message as a `dbwrite:` prefix, so no per-call context argument is needed:
+
+```q
+logger:use`kx.log
+loginst:logger.createLog[]
+logdep:`info`warn`error!(loginst`info;loginst`warn;loginst`error)
+dbwrite:use`di.dbwrite
+dbwrite.init[enlist[`log]!enlist logdep]
+```
+
+---
+
+## The config table
+
+| Column | Type | Description |
+|---|---|---|
+| `tabname` | symbol | Table name, or `` `default `` as a catch-all fallback |
+| `att` | symbol | Attribute applied after sort: `p`,`s`,`g`,`u`, or empty (`` ` ``) for none |
+| `column` | symbol | Column to sort and/or attribute |
+| `sort` | boolean | `1b` — include in the `xasc` sort key; `0b` — attribute only |
+
+Build it directly and load with `setconfig`, or read it from a CSV with `readcsv`. A CSV must have exactly the four columns `tabname,att,column,sort` in **any** order (the result is normalised to canonical order); a missing, extra, or misnamed column raises a clear `di.dbwrite:` error rather than silently mis-parsing.
+
+```
+tabname,att,column,sort
+trade,p,sym,1
+trade,,price,0
+default,,time,1
+```
+
+---
+
+## Functions
+
+| Function | Description |
+|---|---|
+| `init[deps]` | Wire injected dependencies; must be called first |
+| `readcsv[file]` | Read a config CSV and store it in module state |
+| `setconfig[t]` | Store a hand-built config table in module state |
+| `getconfig[]` | Return the currently stored config (`::` if not yet set) |
+| `sort[tabname;dirs]` | Sort on-disk partition(s) for a table and apply attributes per stored config |
+| `savedown[dir;part;tabname;data]` | Write an in-memory table to an HDB partition, sort it, then run gc |
+| `appenddown[dir;part;tabname;data]` | Append rows to an existing partition (no sort) |
+| `applyattr[dloc;colname;att]` | Apply a single kdb+ attribute to an on-disk column |
+
+---
+
+### `init[deps]`
+
+Wire injected dependencies. Must be called before any other function. Also resets the stored sort config to `(::)`.
+
+| Arg | Type | Description |
+|---|---|---|
+| `deps` | dict | Must contain `` `log `` → `` `info`warn`error!(infofn;warnfn;errfn) `` |
+
+Throws (prefixed `di.dbwrite:`) if `deps` is not a dict, `log` is missing, or the log dict lacks any required key.
+
+---
+
+### `readcsv[file]`
+
+Read a config CSV and store it in module state (equivalent to calling `setconfig` with the parsed result). The stored config is used by subsequent calls to `sort` and `savedown`.
+
+| Parameter | Type | Description |
+|---|---|---|
+| `file` | symbol/hsym/string | Path to the CSV. Symbols are coerced with `hsym`; strings are converted via `hsym `$`. Errors (`di.dbwrite:`) if not a symbol or string. |
+
+The CSV is parsed field-by-field and fully validated before storing — it does **not** silently pad, truncate, or coerce malformed rows. A clear `di.dbwrite:` error is raised if: the header is not exactly `tabname,att,column,sort` (any order); any data row does not have exactly four fields; any `sort` value is not `0` or `1`; or any `att` value is not in `` ` `p`s`g`u ``. Column order is normalised to canonical.
+
+```q
+dbwrite.readcsv `:config/sort.csv
+dbwrite.readcsv "config/sort.csv"
+```
+
+---
+
+### `setconfig[t]`
+
+Store a hand-built config table in module state. Alternative to `readcsv` when the config is constructed in-session rather than read from a file. Validates the table before storing — throws (`di.dbwrite:`) on any schema or content error.
+
+| Parameter | Type | Description |
+|---|---|---|
+| `t` | table | Config table with columns `tabname`,`att`,`column`,`sort` |
+
+```q
+dbwrite.setconfig ([] tabname:`trade`default; att:`p`; column:`sym`time; sort:11b)
+```
+
+---
+
+### `getconfig[]`
+
+Return the currently stored sort config. Returns `(::)` if `init` has been called but neither `readcsv` nor `setconfig` has been called yet.
+
+```q
+dbwrite.getconfig[]
+```
+
+---
+
+### `sort[tabname;dirs]`
+
+Sort and apply attributes to the on-disk partition(s) for one table, using the config stored by `readcsv` or `setconfig`. Falls back to the built-in default (sort by `time` ascending) if no config has been loaded.
+
+| Parameter | Type | Description |
+|---|---|---|
+| `tabname` | symbol | Table name. Errors (`di.dbwrite:`) if not a symbol. |
+| `dirs` | hsym, or list of hsyms | Partition directory or directories. |
+
+Row lookup: the table's own rows → the `default` row → otherwise a warn is logged and `()` returned. Each partition is processed independently; a failure on one is logged and does not halt the rest.
+
+```q
+dbwrite.sort[`trade; (`:hdb/2024.01.02/trade; `:hdb/2024.01.03/trade)]
+```
+
+---
+
+### `savedown[dir;part;tabname;data]`
+
+Write an in-memory table to a date-partitioned HDB partition, sort it per the stored config, then run `.Q.gc[]`. Enumerates symbol columns against the HDB sym file before writing. Sorting and attributes are applied by `sort` *after* the write — so an attribute like `p#` is only applied once its column is correctly grouped.
+
+| Parameter | Type | Description |
+|---|---|---|
+| `dir` | hsym | HDB root directory (e.g. `` `:hdb ``). |
+| `part` | date/month/int | Partition value. |
+| `tabname` | symbol | Table name — determines the partition subdirectory. |
+| `data` | table | In-memory table to write. |
+
+Throws on write failure.
+
+```q
+dbwrite.savedown[`:hdb; 2024.01.02; `trade; data]
+```
+
+---
+
+### `appenddown[dir;part;tabname;data]`
+
+Append rows to an existing on-disk partition (enumerates syms); does **not** sort. Keeping sort separate allows multiple intraday appends without re-sorting a growing partition on each call — sort once when the partition is complete.
+
+| Parameter | Type | Description |
+|---|---|---|
+| `dir` | hsym | HDB root directory. |
+| `part` | date/month/int | Partition value. |
+| `tabname` | symbol | Table name. |
+| `data` | table | Rows to append. |
+
+Throws (prefixed `di.dbwrite:`) if the partition does not exist, or on write failure.
+
+```q
+/ intraday: append each batch as it arrives
+dbwrite.appenddown[`:hdb; 2024.01.02; `trade; batch]
+/ end-of-day: sort once when done
+dbwrite.sort[`trade; .Q.par[`:hdb; 2024.01.02; `trade]]
+```
+
+---
+
+### `applyattr[dloc;colname;att]`
+
+Apply a single kdb+ attribute to one on-disk column (best-effort: logs and swallows errors so a run continues). A non-attribute `att` (the empty sentinel or any value outside `` `p`s`g`u ``) is a silent no-op.
+
+```q
+dbwrite.applyattr[`:hdb/2024.01.02/trade; `sym; `p]
+```
+
+---
+
+## Running tests
+
+```q
+k4unit:use`di.k4unit
+k4unit.moduletest`di.dbwrite
+```
+
+The suite injects monadic mock loggers (`{[msg] ...}`): a no-op logger, and a capturing logger that records `(level;msg)` so log behaviour can be asserted. It also wires a real `kx.log` instance through `init` to confirm the module works end-to-end against the system logger. On-disk behaviour (sort, attributes, `savedown`/`appenddown`) is exercised against real splayed partitions and cleaned up afterwards. It covers: dependency-injection validation; `readcsv` stores-and-verifies / column-order independence / header-validation failures; `setconfig` happy path and validation failures; `sort` edge cases / resolution / on-disk results / multi-dir / non-fatal partition failure; `savedown` write+sort (default and explicit config, and a table without `sym`); `appenddown` append-without-sort then explicit sort, and the non-existent-partition error; `applyattr`; the `dbwrite:`-prefixed logging contract; and the real `kx.log` integration.
+
+---
+
+## Exported symbols
+
+```q
+export:([init;readcsv;setconfig;getconfig;sort;applyattr;savedown;appenddown])
+```