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https://issues.apache.org/jira/browse/HAWQ-577?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15215337#comment-15215337
]
ASF GitHub Bot commented on HAWQ-577:
-------------------------------------
Github user shivzone commented on a diff in the pull request:
https://github.com/apache/incubator-hawq/pull/522#discussion_r57666661
--- Diff:
pxf/pxf-service/src/main/java/org/apache/hawq/pxf/service/MetadataResponseFormatter.java
---
@@ -46,76 +45,49 @@
* @return JSON formatted response
* @throws IOException if converting the data to JSON fails
*/
- public static String formatResponseString(List<Metadata> metadataList)
throws IOException {
- return MetadataResponseFormatter.metadataToJSON(metadataList);
- }
-
- /**
- * Serializes a metadata in JSON,
- * To be used as the result string for HAWQ.
- * An example result is as follows:
- *
- *
{"PXFMetadata":[{"item":{"path":"default","name":"t1"},"fields":[{"name":"a","type":"int"},{"name":"b","type":"float"}]}]}
- */
- private static String metadataToJSON(List<Metadata> metadataList)
throws IOException {
-
- if (metadataList == null || metadataList.isEmpty()) {
- return METADATA_DEFAULT_RESPONSE;
+ public static MetadataResponse formatResponse(List<Metadata>
metadataList, String path) throws IOException {
+ /* print the fragment list to log when in debug level */
+ if (LOG.isDebugEnabled()) {
+ MetadataResponseFormatter.printMetadata(metadataList, path);
}
- StringBuilder result = null;
-
- for(Metadata metadata: metadataList) {
- if(metadata == null) {
- throw new IllegalArgumentException("metadata object is
null - cannot serialize");
- }
- if ((metadata.getFields() == null) ||
metadata.getFields().isEmpty()) {
- throw new IllegalArgumentException("metadata for " +
metadata.getItem() + " contains no fields - cannot serialize");
- }
- if (result == null) {
- result = new StringBuilder("{\"PXFMetadata\":["); /*
prefix info */
- } else {
- result.append(",");
- }
-
- ObjectMapper mapper = new ObjectMapper();
- mapper.setSerializationInclusion(Inclusion.NON_EMPTY); //
ignore empty fields
- result.append(mapper.writeValueAsString(metadata));
- }
-
- return result.append("]}").toString(); /* append suffix info */
-
+ return new MetadataResponse(metadataList);
}
/**
* Converts metadata list to a readable string.
* Intended for debugging purposes only.
*/
- private static String metadataToString(List<Metadata> metadataList) {
- StringBuilder result = new StringBuilder("Metadata:");
+ private static void printMetadata(List<Metadata> metadataList, String
path) {
+ LOG.debug("Metadata List for path " + path + ": ");
+
+ if (null == metadataList || metadataList.isEmpty()) {
+ LOG.debug("No metadata");
+ return;
+ }
for(Metadata metadata: metadataList) {
- result.append(" Metadata for item \"");
+ StringBuilder result = new StringBuilder();
if (metadata == null) {
- return "No metadata";
+ result.append("None");
--- End diff --
This is just used for logging and not for the response. Defining constants
just for log message seems an overkill
> Stream PXF metadata response
> -----------------------------
>
> Key: HAWQ-577
> URL: https://issues.apache.org/jira/browse/HAWQ-577
> Project: Apache HAWQ
> Issue Type: Bug
> Components: PXF
> Reporter: Shivram Mani
> Assignee: Shivram Mani
>
> getMetadata api returns the metadata corresponding to the user specified
> pattern. There is no limit to the #of tables the pattern can correspond do
> and the current approach of building in memory the json object might not
> scale.
> We needed to serialize them inside a streaming object similar to the approach
> used for streaming the FragmentsResponse
> The same applies also for the debug function that prints metadata of all the
> items - if there are too many of them the StringBuilder will run out of
> memory. The solution in the fragments case was to print a log of one fragment
> at a time.
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