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A Storr with Time-Travel

Source: R/storr_timetravel.R
storr_timetravel.Rd

Generate an instance of StorrTimeTravel, a variant of TileDBStorr designed to query key-value data at specific points in time and in read-only mode with no write capabilities.

Usage

storr_timetravel(uri, default_namespace = "objects", context = NULL,
  timestamp = NULL)

Arguments

uri

The URI path of storr.

default_namespace

The default namespace: "objects".

context

Optional tiledb_ctx object.

timestamp

Set a TileDB timestamp range that the resource will be opened at. Effective only for "READ" mode. Valid options:

  • A NULL value (default)

  • An R object coercible to POSIXct with length 1 which used for end timestamp, or length 2 with start, end timestamps

  • An object of class tiledb_timestamp. See set_tiledb_timestamp()

Set a new timestamp with active field $timestamp, see examples.

Value

An object of class StorrTimeTravel, R6.

Class Methods Summary

For complete definitions, see Methods section in StorrTimeTravel.

Active Fields

  • timestamp - Get or set a TileDB timestamp range that the 'storr' will be opened at.

Single Key-Value Operations

  • get() - Retrieve an object by key-namespace pair

  • get_value() - Retrieve an object given its hash

Multiple Key-Value Operations

  • mget() - Get multiple objects by keys

  • mget_value() - Get multiple objects by their hashes

Metadata Operations

  • get_keymeta() - Retrieve metadata for a key

  • mget_keymeta() - Retrieve metadata for multiple keys

Object Hash Management

  • get_hash() - Get hash value for a key-namespace pair

  • mget_hash() - Get hash values for multiple keys

Key Management

  • exists() - Check if key-namespace pair(s) exist

  • exists_object() - Check if object(s) with given hash(es) exist

Expiration Management

  • keys_with_expiration() - List keys that have expiration timestamps

  • expired_keys() - Get keys that have already expired

  • has_expired_keys() - Check if any keys are expired

Listing

  • list() - List all keys in a namespace

  • list_hashes() - List all stored object hashes

  • list_unused_hashes() - List all stored object unused hashes

  • list_namespaces() - List all namespaces

Storage Management

  • index_export() - Export object index as data.table

  • export() - Export objects to another storr/list/environment

  • export_tdb() - Export objects to another TileDB storr

Examples

if (FALSE) { # \dontrun{
# URI path
uri <- tempfile()
sto <- storr_tiledb(uri, init = TRUE)

# set key-values
t0 <- Sys.time()
sto$set("a", 1)

t1 <- Sys.time()
sto$set("b", 2)

t2 <- Sys.time()

# Open storr with time-travel support at t0
stor <- storr_timetravel(uri, timestamp = t0)

# Read at t0
stor$list_hashes() # character(0), no hashes at t0

stor$get("a") #  key 'a' ('objects') not found

# Read at t1
stor$timestamp <- t1
stor$get("a") # 1
stor$get("b") # key 'b' ('objects') not found

# Read at t2
stor$timestamp <- t2
sto$get("b") # 2

} # }