Exports a large object to file

Exports a large object from the database to a file on disk. This function uses PostgreSQL's lo_export() function which efficiently streams the data directly to disk without loading it into memory, making it suitable for very large objects (GB+) that would cause memory issues with lo_get(). This function must be called within a transaction.

Usage

postgresExportLargeObject(conn, oid, filepath)

Arguments

conn

a PqConnection object, produced by DBI::dbConnect()

oid

the object identifier (Oid) of the large object to export

filepath

a path where the large object should be exported

Value

invisible NULL on success, or stops with an error

Examples

if (FALSE) { # \dontrun{
con <- postgresDefault()
filepath <- 'your_image.png'
dbWithTransaction(con, {
  oid <- postgresImportLargeObject(con, filepath)
})
# Later, export the large object back to a file
dbWithTransaction(con, {
  postgresExportLargeObject(con, oid, 'exported_image.png')
})
} # }