Glossary

Glossary

Access key (jza1-...). A key issued by a shared file's owner that opens only the partitions and column groups it was granted. Read-only. See Access Control.

Access-controlled file (shared file). A file with an owner key and access keys, signed by the owner.

Analyze. explain(filter, { analyze: true }): runs a query and reports what it read (rows, bytes, chunks, index sections, column streams).

Append. A change written at the end of a file without touching existing bytes. Cheap; compact later.

Catalog. The file's description of itself: header, directories, statistics, indexes and key slots. Stored at the end, so writers can stream.

Chunk. A block of rows (4,096 by default), stored column by column, compressed and encrypted on its own. The unit a query reads.

Chunk statistics. Each chunk's minimum, maximum and null count per column. Let queries skip chunks that can't match.

Codec. The compression of each section: deflate (default), brotli (smaller; not in browsers) or none.

Column group. A named set of columns in a shared file, granted to keys separately. Columns in no named group form the default group *.

Column stream. One column's values within one chunk. A query decodes only the streams it needs.

Compact. A rewrite that drops deleted and replaced rows, removes expired grants and re-locks the file with fresh secrets. regroup also gathers each partition's rows together.

Compact indexes (compactIndexes). Sorted indexes stored as differences between keys: much smaller for numbers and dates. Readers need 1.2 or later (reader feature index-deltas).

Embedded file. Any file (PDF, image, HTML, font, video) stored inside a .jzm file, in 256 KiB blocks.

Export shape. A JSON template that turns flat rows into nested JSON or XML. See Export Shapes.

File id. 16 random bytes identifying one version of a file, readable without a key (inspect()). A key service uses it with a key id to issue unlock tokens.

Filter. The JSON query language shared by JavaScript, .NET, browsers, the CLI and GraphQL. See Filter Language.

Grant. What an access key may see: rows (partitions), columns (column groups), files, a label, an expiry and a mode.

Index. An optional per-column structure: sorted (equality, ranges, prefixes) or trigram (text contains).

Key (jzk1-...). 32 random bytes as text with a checksum. Encrypts a file, or is the owner key of a shared file.

Key service. Your server that issues unlock tokens for online grants, and may require 2FA first.

Key slot. The part of a shared file holding one access key's granted secrets.

Keyset paging. Asking for the rows after the last one you saw ({ id: { gt: lastId } }) instead of using a large offset: stays fast however deep you page.

Metadata. Your own key/value information stored in a file (source, export date...). Visible to every key holder of a shared file.

Online grant. A grant whose holder also needs an unlock token from the key service to open the file.

Offline grant. A grant whose expiry the library enforces on the device (the default).

Owner key. The key of a shared file: reads everything, is the only key that can change the file or grant access, and signs the file. Keep it on servers; browsers refuse it.

Package. A file's embedded website: an entry page and the files it uses, shown by the viewer and printed by renderPdf.

Partition. All rows sharing a value of the partitionBy column in a shared file: the unit of row access.

Priority. memory, balanced or speed: what reads and writes favour where memory and speed pull apart.

Reader feature. A capability a file announces because readers must understand it; readers that don't refuse the file and name the feature.

Section. Any stored unit of a file (a chunk part, an index page, the header...), with its own envelope, CRC and key.

Select. The query option listing the columns to return; only those (and the filter's) are decoded.

sortedBy. The declared order of a file's rows. Makes lookups and ranges on the first column skip to the right chunks with no index.

Submission key. A key derived from an access key, sealed in the shared file, used to lock records sent back to the owner. See Sending Records Back.

Table. A set of columns and rows. A file has one by default and can hold several.

Trailer. The last 44 bytes of a file: where the header is, a CRC, and the magic JZM1.

Unlock token (jzu1-...). What an online grant needs, besides the access key, to open a file.

Viewer. The web app that opens .jzm files in a browser. See Viewer and Browser.