---
name: "Prophet::Replica::prophet"
section: "3pm"
platform: "linux"
package: "libprophet-perl"
version: "0.743-1"
release: "Debian 7 (Wheezy)"
platforms: ["linux"]
url: "https://new.carta.tech/Prophet::Replica::prophet"
---

# Prophet::Replica::prophet(3pm)

## Replica Format

overview

```
 $URL
    /<db-uuid>/
        /replica-uuid
        /latest-sequence-no
        /replica-version
        /cas/records/<substr(sha1,0,1)>/substr(sha1,1,1)/<sha1>
        /cas/changesets/<substr(sha1,0,1)>/substr(sha1,1,1)/<sha1>
        /records (optional?)
            /<record type> (for resolution is actually _prophet-resolution-<cas-key>)
                /<record uuid> which is a file containing a list of 0 or more rows
                    last-changed-sequence-no : cas key

        /changesets.idx

            index which has records:
                each record is : local-replica-seq-no : original-uuid : original-seq-no : cas key
            ...

        /resolutions/
            /replica-uuid
            /latest-sequence-no
            /cas/<substr(sha1,0,1)>/substr(sha1,1,1)/<sha1>
            /content (optional?)
                /_prophet-resolution-<cas-key>   (cas-key == a hash the conflicting change)
                    /<record uuid>  (record uuid == the originating replica)
                        last-changed-sequence-no : <cas key to the content of the resolution>

            /changesets.idx
                index which has records:
                    each record is : local-replica-seq-no : original-uuid : original-seq-no : cas key
                ...
```

Inside the top level directory for the mirror, you'll find a directory named as **a hex-encoded UUID**. This directory is the root of the published replica. The uuid uniquely identifes the database being replicated. All replicas of this database will share the same UUID.

Inside the **\<db-uuid**\> directory, are a set of files and directories that make up the actual content of the database replica:

- "replica-uuid"

  Contains the replica's hex-encoded UUID.

- "replica-version"

  Contains a single integer that defines the replica format.

  The current replica version is 1.

- "latest-sequence-no"

  Contains a single integer, the replica's most recent sequence number.

- "cas/records"

  - "cas/changesets"

  The `"cas"` directory holds changesets and records, each keyed by a hex-encoded hash of the item's content. Inside the `"cas"` directory, you'll find a two-level deep directory tree of single-character hex digits.  You'll find  the changeset with the sha1 digest  `"f4b7489b21f8d107ad8df78750a410c028abbf6c"` inside `"cas/changesets/f/4/f4b7489b21f8d107ad8df78750a410c028abbf6c"`.

  You'll find the record with the sha1 digest `"dd6fb674de879a1a4762d690141cdfee138daf65"` inside `"cas/records/d/d/dd6fb674de879a1a4762d690141cdfee138daf65"`.

  TODO: define the format for changesets and records

- "records"

  Files inside the `"records"` directory are index files which list off all published versions of a record and the key necessary to retrieve the record from the *content-addressed store*.

  Inside the `"records"` directory, you'll     warn "Got types ".join(',',@types);find directories named for each `"type"` in your database. Inside each `"type"` directory, you'll find a two-level directory tree of single hexadecimal digits. You'll find the record with the type \<Foo\> and the UUID `"29A3CA16-03C5-11DD-9AE0-E25CFCEE7EC4"` stored in

  ```
   records/Foo/2/9/29A3CA16-03C5-11DD-9AE0-E25CFCEE7EC4
  ```

  The format of record files is:

  ```
      <unsigned-long-int: last-changed-sequence-no><40 chars of hex: cas key>
  ```

  The file is sorted in asecnding order by revision id.

- "changesets.idx"

  The `"changesets.idx"` file lists each changeset in this replica and provides an index into the **content-addressed storage** to fetch the content of the changeset.

  The format of record files is:

  ```
      <unsigned-long-int: sequence-no><16 bytes: changeset original source uuid><unsigned-long-int: changeset original source sequence no><16 bytes: cas key - sha1 sum of the changeset's content>
  ```

  The file is sorted in ascending order by revision id.

- "resolutions"

  - TODO DOC RESOLUTIONS

    ### BUILD

Open a connection to the prophet replica source identified by `"$self-"`url\>.

### replica\_version

Returns this replica's version.

### set\_replica\_version

Sets the replica's version to the given integer.

### uuid

Return the replica's UUID

## Internals of record handling

### changesets\_for\_record { uuid =\> $uuid, type =\> $type, limit =\> $int }

Returns an ordered set of changeset objects for all changesets containing changes to this object.

Note that changesets may include changes to other records

If "limit" is specified, only returns that many changesets (starting from record creation).