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new 77812b4 Update client documentation (#144)
77812b4 is described below
commit 77812b47d32383b4a3eb6f86c2a650a3e8d12411
Author: Mike Walch <mwa...@apache.org>
AuthorDate: Tue Jan 29 16:34:50 2019 -0500
Update client documentation (#144)
---
_docs-2/getting-started/clients.md | 75 +++++++++++++++++++++-----------------
1 file changed, 42 insertions(+), 33 deletions(-)
diff --git a/_docs-2/getting-started/clients.md
b/_docs-2/getting-started/clients.md
index cff9086..68ac3ce 100644
--- a/_docs-2/getting-started/clients.md
+++ b/_docs-2/getting-started/clients.md
@@ -115,19 +115,12 @@ changes to the columns of a single row. The changes are
made atomically in the
TabletServer. Clients then add Mutations to a [BatchWriter] which submits them
to
the appropriate TabletServers.
-Mutations can be created thus:
+The code below shows how a Mutation is created.
```java
-Text rowID = new Text("row1");
-Text colFam = new Text("myColFam");
-Text colQual = new Text("myColQual");
-ColumnVisibility colVis = new ColumnVisibility("public");
-long timestamp = System.currentTimeMillis();
-
-Value value = new Value("myValue".getBytes());
-
-Mutation mutation = new Mutation(rowID);
-mutation.put(colFam, colQual, colVis, timestamp, value);
+Mutation mutation = new Mutation("row1");
+mutation.at().family("myColFam1").qualifier("myColQual1").visibility("public").put("myValue1");
+mutation.at().family("myColFam2").qualifier("myColQual2").visibility("public").put("myValue2");
```
### BatchWriter
@@ -138,16 +131,14 @@ amortize network overhead. Care must be taken to avoid
changing the contents of
any Object passed to the BatchWriter since it keeps objects in memory while
batching.
-Mutations are added to a BatchWriter thus:
+The code below shows how a Mutation is added to a BatchWriter:
```java
-// BatchWriterConfig has reasonable defaults
-BatchWriterConfig config = new BatchWriterConfig();
-config.setMaxMemory(10000000L); // bytes available to batchwriter for
buffering mutations
-
-BatchWriter writer = client.createBatchWriter("table", config)
-writer.addMutation(mutation);
-writer.close();
+try (BatchWriter writer = client.createBatchWriter("mytable")) {
+ Mutation m = new Mutation("row1");
+ m.at().family("myfam").qualifier("myqual").visibility("public").put("myval");
+ writer.addMutation(m);
+}
```
For more example code, see the [batch writing and scanning example][batch].
@@ -224,21 +215,37 @@ to efficiently return ranges of consecutive keys and
their associated values.
### Scanner
-To retrieve data, Clients use a [Scanner], which acts like an Iterator over
-keys and values. Scanners can be configured to start and stop at particular
keys, and
+To retrieve data, create a [Scanner] using [AccumuloClient]. A Scanner acts
like an Iterator over
+keys and values in the table.
+
+If a [Scanner] is created without [Authorizations], it uses all
[Authorizations] granted
+to the user that created the [AccumuloClient]:
+
+```java
+Scanner s = client.createScanner("table");
+```
+
+A scanner can also be created to only use a subset of a user's
[Authorizations].
+
+```java
+Scanner s = client.createScanner("table", new Authorizations("public"));
+```
+
+Scanners can be configured to start and stop at particular keys, and
to return a subset of the columns available.
```java
-// specify which visibilities we are allowed to see
+// return data with visibilities that match specified auths
Authorizations auths = new Authorizations("public");
-Scanner scan = client.createScanner("table", auths);
-scan.setRange(new Range("harry","john"));
-scan.fetchColumnFamily(new Text("attributes"));
+try (Scanner scan = client.createScanner("table", auths)) {
+ scan.setRange(new Range("harry","john"));
+ scan.fetchColumnFamily(new Text("attributes"));
-for (Entry<Key,Value> entry : scan) {
- Text row = entry.getKey().getRow();
- Value value = entry.getValue();
+ for (Entry<Key,Value> entry : scan) {
+ Text row = entry.getKey().getRow();
+ Value value = entry.getValue();
+ }
}
```
@@ -281,12 +288,13 @@ TabletServers in parallel.
ArrayList<Range> ranges = new ArrayList<Range>();
// populate list of ranges ...
-BatchScanner bscan = client.createBatchScanner("table", auths, 10);
-bscan.setRanges(ranges);
-bscan.fetchColumnFamily("attributes");
+try (BatchScanner bscan = client.createBatchScanner("table", auths, 10)) {
+ bscan.setRanges(ranges);
+ bscan.fetchColumnFamily("attributes");
-for (Entry<Key,Value> entry : bscan) {
- System.out.println(entry.getValue());
+ for (Entry<Key,Value> entry : bscan) {
+ System.out.println(entry.getValue());
+ }
}
```
@@ -371,3 +379,4 @@ This page covers Accumulo client basics. Below are links
to additional document
[isolation]:
https://github.com/apache/accumulo-examples/blob/master/docs/isolation.md
[accumulo-client.properties]: {% durl
configuration/files#accumulo-clientproperties %}
[table.durability]: {% purl table.durability %}
+[Authorizations]: {% jurl org.apache.accumulo.core.security.Authorizations %}
