10.6. Load CSV
LOAD CSV
allows you to import data from CSV files.
It is required to specify an identifier for the CSV data using AS
.
See the examples for further details.
Import data from a CSV file
To import data from a CSV file into Neo4j, you can use LOAD CSV
to get the data into your query.
Then you write it to your database using the normal updating clauses of Cypher.
artists.csv.
"1","ABBA","1992" "2","Roxette","1986" "3","Europe","1979" "4","The Cardigans","1992"
Query.
LOAD CSV FROM 'http://docs.neo4j.org/chunked/2.1.2/csv/artists.csv' AS line CREATE (:Artist { name: line[1], year: toInt(line[2])})
A new node with the Artist
label is created for each row in the CSV file.
In addition, two columns from the CSV file are set as properties on the nodes.
Result
Nodes created: 4 |
---|
Properties set: 8 |
Labels added: 4 |
|
Try this query live. none LOAD CSV FROM 'http://docs.neo4j.org/chunked/2.1.2/csv/artists.csv' AS line CREATE (:Artist {name: line[1], year: toInt(line[2])})
Import data from a CSV file containing headers
When your CSV file has headers, you can view each row in the file as a map instead of as an array of strings.
artists-with-headers.csv.
"Id","Name","Year" "1","ABBA","1992" "2","Roxette","1986" "3","Europe","1979" "4","The Cardigans","1992"
Query.
LOAD CSV WITH HEADERS FROM 'http://docs.neo4j.org/chunked/2.1.2/csv/artists-with-headers.csv' AS line CREATE (:Artist { name: line.Name, year: toInt(line.Year)})
This time, the file starts with a single row containing column names.
Indicate this using WITH HEADERS
and you can access specific fields by their corresponding column name.
Result
Nodes created: 4 |
---|
Properties set: 8 |
Labels added: 4 |
|
Try this query live. none LOAD CSV WITH HEADERS FROM 'http://docs.neo4j.org/chunked/2.1.2/csv/artists-with-headers.csv' AS line CREATE (:Artist {name: line.Name, year: toInt(line.Year)})
Import data from a CSV file with a custom field delimiter
Sometimes, your CSV file has other field delimiters than commas.
You can specify which delimiter your file uses using FIELDTERMINATOR
.
artists-fieldterminator.csv.
"1";"ABBA";"1992" "2";"Roxette";"1986" "3";"Europe";"1979" "4";"The Cardigans";"1992"
Query.
LOAD CSV FROM 'http://docs.neo4j.org/chunked/2.1.2/csv/artists-fieldterminator.csv' AS line FIELDTERMINATOR ';' CREATE (:Artist { name: line[1], year: toInt(line[2])})
As values in this file are separated by a semicolon, a custom FIELDTERMINATOR
is specified in the LOAD CSV
clause.
Result
Nodes created: 4 |
---|
Properties set: 8 |
Labels added: 4 |
|
Try this query live. none LOAD CSV FROM 'http://docs.neo4j.org/chunked/2.1.2/csv/artists-fieldterminator.csv' AS line FIELDTERMINATOR ';' CREATE (:Artist {name: line[1], year: toInt(line[2])})
Importing large amounts of data
If the CSV file contains a significant number of rows (approaching hundreds of thousands or millions), USING PERIODIC COMMIT
can be used to instruct Neo4j to perform a commit after a number of rows.
This reduces the memory overhead of the transaction state.
By default, the commit will happen every 1000 rows.
For more information, see Section 11.9, “Using Periodic Commit”.
Query.
USING PERIODIC COMMIT LOAD CSV FROM 'http://docs.neo4j.org/chunked/2.1.2/csv/artists.csv' AS line CREATE (:Artist { name: line[1], year: toInt(line[2])})
Result
Nodes created: 4 |
---|
Properties set: 8 |
Labels added: 4 |
|
Try this query live. none USING PERIODIC COMMIT LOAD CSV FROM 'http://docs.neo4j.org/chunked/2.1.2/csv/artists.csv' AS line CREATE (:Artist {name: line[1], year: toInt(line[2])})
Import data containing escape characters
Query.
LOAD CSV FROM 'http://docs.neo4j.org/chunked/2.1.2/csv/artists-with-escape-char.csv' AS line CREATE (a:Artist { name: line[1], year: toInt(line[2])}) RETURN a.name AS name
Result
name |
---|
1 row |
Nodes created: 1 |
Properties set: 2 |
Labels added: 1 |
|
Try this query live. none LOAD CSV FROM 'http://docs.neo4j.org/chunked/2.1.2/csv/artists-with-escape-char.csv' AS line CREATE (a:Artist {name: line[1], year: toInt(line[2])}) return a.name as name
Setting the rate of periodic commits
You can set the number of rows as in the example, where it is set to 500 rows.
Query.
USING PERIODIC COMMIT 500 LOAD CSV FROM 'http://docs.neo4j.org/chunked/2.1.2/csv/artists.csv' AS line CREATE (:Artist { name: line[1], year: toInt(line[2])})
Result
Nodes created: 4 |
---|
Properties set: 8 |
Labels added: 4 |
|
Try this query live. none USING PERIODIC COMMIT 500 LOAD CSV FROM 'http://docs.neo4j.org/chunked/2.1.2/csv/artists.csv' AS line CREATE (:Artist {name: line[1], year: toInt(line[2])})
CSV file format
The CSV file supported by the cypher LOAD CSV
must have the following characteristics:
- the character encoding is UTF-8;
-
the end line termination is system dependent, e.g., it is
\n
on unix or\r\n
on windows; -
the default field terminator is
,
; -
the field terminator character can be change by using the option
FIELDTERMINATOR
available in theLOAD CSV
command; - quoted strings are allowed in the CSV file and the quotes are dropped when reading the data;
-
the character for string quotation is double quote
"
; -
the escape character is
\
.