use of com.amazonaws.athena.connectors.dynamodb.constants.DynamoDBConstants.EXPRESSION_NAMES_METADATA in project aws-athena-query-federation by awslabs.
the class DynamoDBRecordHandler method buildReadRequest.
/*
Converts a split into a Query or Scan request
*/
private AmazonWebServiceRequest buildReadRequest(Split split, String tableName, Schema schema) {
validateExpectedMetadata(split.getProperties());
// prepare filters
String rangeKeyFilter = split.getProperty(RANGE_KEY_FILTER_METADATA);
String nonKeyFilter = split.getProperty(NON_KEY_FILTER_METADATA);
Map<String, String> expressionAttributeNames = new HashMap<>();
Map<String, AttributeValue> expressionAttributeValues = new HashMap<>();
if (rangeKeyFilter != null || nonKeyFilter != null) {
try {
expressionAttributeNames.putAll(Jackson.getObjectMapper().readValue(split.getProperty(EXPRESSION_NAMES_METADATA), STRING_MAP_TYPE_REFERENCE));
expressionAttributeValues.putAll(Jackson.getObjectMapper().readValue(split.getProperty(EXPRESSION_VALUES_METADATA), ATTRIBUTE_VALUE_MAP_TYPE_REFERENCE));
} catch (IOException e) {
throw new RuntimeException(e);
}
}
// Only read columns that are needed in the query
String projectionExpression = schema.getFields().stream().map(field -> {
String aliasedName = DDBPredicateUtils.aliasColumn(field.getName());
expressionAttributeNames.put(aliasedName, field.getName());
return aliasedName;
}).collect(Collectors.joining(","));
boolean isQuery = split.getProperty(SEGMENT_ID_PROPERTY) == null;
if (isQuery) {
// prepare key condition expression
String indexName = split.getProperty(INDEX_METADATA);
String hashKeyName = split.getProperty(HASH_KEY_NAME_METADATA);
String hashKeyAlias = DDBPredicateUtils.aliasColumn(hashKeyName);
String keyConditionExpression = hashKeyAlias + " = " + HASH_KEY_VALUE_ALIAS;
if (rangeKeyFilter != null) {
keyConditionExpression += " AND " + rangeKeyFilter;
}
expressionAttributeNames.put(hashKeyAlias, hashKeyName);
expressionAttributeValues.put(HASH_KEY_VALUE_ALIAS, Jackson.fromJsonString(split.getProperty(hashKeyName), AttributeValue.class));
return new QueryRequest().withTableName(tableName).withIndexName(indexName).withKeyConditionExpression(keyConditionExpression).withFilterExpression(nonKeyFilter).withExpressionAttributeNames(expressionAttributeNames).withExpressionAttributeValues(expressionAttributeValues).withProjectionExpression(projectionExpression);
} else {
int segmentId = Integer.parseInt(split.getProperty(SEGMENT_ID_PROPERTY));
int segmentCount = Integer.parseInt(split.getProperty(SEGMENT_COUNT_METADATA));
return new ScanRequest().withTableName(tableName).withSegment(segmentId).withTotalSegments(segmentCount).withFilterExpression(nonKeyFilter).withExpressionAttributeNames(expressionAttributeNames.isEmpty() ? null : expressionAttributeNames).withExpressionAttributeValues(expressionAttributeValues.isEmpty() ? null : expressionAttributeValues).withProjectionExpression(projectionExpression);
}
}
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