Hive是如何解析SQL的呢,首先拿hive的建表语句来举例,比如下面的建表语句

create table test(id int,name string)row format delimited fields terminated by '\t';

然后使用hive的show create table语句来查看创建的表结构，这是一张text表

CREATE TABLE `test`(
`id` int,
`name` string)
ROW FORMAT SERDE
'org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe'
WITH SERDEPROPERTIES (
'field.delim'='\t',
'serialization.format'='\t')
STORED AS INPUTFORMAT
'org.apache.hadoop.mapred.TextInputFormat'
OUTPUTFORMAT
'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat'
LOCATION
'hdfs://master:8020/user/hive/warehouse/test'
TBLPROPERTIES (
'transient_lastDdlTime'='1568561230')

当然还有其他各种建表语句，比如

csv表

CREATE EXTERNAL TABLE `default.test_1`(
`key` string COMMENT 'from deserializer',
`value` string COMMENT 'from deserializer')
ROW FORMAT SERDE
'org.apache.hadoop.hive.serde2.OpenCSVSerde'
WITH SERDEPROPERTIES (
'escapeChar'='\\',
'quoteChar'='\'',
'separatorChar'='\t')
STORED AS INPUTFORMAT
'org.apache.hadoop.mapred.TextInputFormat'
OUTPUTFORMAT
'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat'
LOCATION
'hdfs://master:8020/user/hive/warehouse/test'
TBLPROPERTIES (
'COLUMN_STATS_ACCURATE'='false',
'numFiles'='0',
'numRows'='-1',
'rawDataSize'='-1',
'totalSize'='0',
'transient_lastDdlTime'='xxxx')

parquet表

CREATE TABLE `default.test`(
`time` string,
`server` int,
`id` bigint)
PARTITIONED BY (
`ds` string)
ROW FORMAT SERDE
'org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe'
WITH SERDEPROPERTIES (
'field.delim'='\t',
'serialization.format'='\t')
STORED AS INPUTFORMAT
'org.apache.hadoop.hive.ql.io.parquet.MapredParquetInputFormat'
OUTPUTFORMAT
'org.apache.hadoop.hive.ql.io.parquet.MapredParquetOutputFormat'
LOCATION
'hdfs://master:8020/user/hive/warehouse/test'
TBLPROPERTIES (
'transient_lastDdlTime'='xxxx')

json表

CREATE EXTERNAL TABLE `default.test`(
`titleid` string COMMENT 'from deserializer',
`timestamp` string COMMENT 'from deserializer')
ROW FORMAT SERDE
'org.openx.data.jsonserde.JsonSerDe'
STORED AS INPUTFORMAT
'org.apache.hadoop.mapred.TextInputFormat'
OUTPUTFORMAT
'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat'
LOCATION
'hdfs://master:8020/user/hive/warehouse/test'
TBLPROPERTIES (
'COLUMN_STATS_ACCURATE'='false',
'numFiles'='0',
'numRows'='-1',
'rawDataSize'='-1',
'totalSize'='0',

es表

CREATE EXTERNAL TABLE `default.test`(
`id` string COMMENT 'from deserializer',
`ts` string COMMENT 'from deserializer', ')
PARTITIONED BY (
`ds` string)
ROW FORMAT SERDE
'org.elasticsearch.hadoop.hive.EsSerDe'
STORED BY
'org.elasticsearch.hadoop.hive.EsStorageHandler'
WITH SERDEPROPERTIES (
'serialization.format'='1')
LOCATION
'hdfs://master:8020/user/hive/warehouse/test'
TBLPROPERTIES (
'es.index.auto.create'='yes',
'es.index.read.missing.as.empty'='yes',
'es.nodes'='host1,host2',
'es.port'='9200',
'es.resource'='index1/type1',

使用thrift的binary表

CREATE EXTERNAL TABLE `default.test`(
`bbb` string COMMENT 'from deserializer',
`aaa` string COMMENT 'from deserializer')
COMMENT 'aas'
PARTITIONED BY (
`ds` string COMMENT '日期分区')
ROW FORMAT SERDE
'org.apache.hadoop.hive.serde2.thrift.ThriftDeserializer'
WITH SERDEPROPERTIES (
'serialization.class'='com.xxx.xxx.xxx.tables.v1.XXXX',
'serialization.format'='org.apache.thrift.protocol.TCompactProtocol')
STORED AS INPUTFORMAT
'org.apache.hadoop.mapred.SequenceFileInputFormat'
OUTPUTFORMAT
'org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat'
LOCATION
'hdfs://master:8020/user/hive/warehouse/test'
TBLPROPERTIES (
'transient_lastDdlTime'='xxxxxx')

等等

可以查看show create table的hive源码

https://github.com/apache/hive/blob/68ae4a5cd1b916098dc1deb2bcede5f862afd80e/ql/src/java/org/apache/hadoop/hive/ql/ddl/table/creation/ShowCreateTableOperation.java

其中可以看出hive表的一些基本信息

private static final String CREATE_TABLE_TEMPLATE =
"CREATE <" + TEMPORARY + "><" + EXTERNAL + ">TABLE `<" + NAME + ">`(\n" +
"<" + LIST_COLUMNS + ">)\n" +
"<" + COMMENT + ">\n" +
"<" + PARTITIONS + ">\n" +
"<" + BUCKETS + ">\n" +
"<" + SKEWED + ">\n" +
"<" + ROW_FORMAT + ">\n" +
"<" + LOCATION_BLOCK + ">" +
"TBLPROPERTIES (\n" +
"<" + PROPERTIES + ">)\n";

private String getCreateTableCommand(Table table) {
ST command = new ST(CREATE_TABLE_TEMPLATE);

command.add(NAME, desc.getTableName());  
command.add(TEMPORARY, getTemporary(table));  
command.add(EXTERNAL, getExternal(table));  
command.add(LIST\_COLUMNS, getColumns(table));  
command.add(COMMENT, getComment(table));  
command.add(PARTITIONS, getPartitions(table));  
command.add(BUCKETS, getBuckets(table));  
command.add(SKEWED, getSkewed(table));  
command.add(ROW\_FORMAT, getRowFormat(table));  
command.add(LOCATION\_BLOCK, getLocationBlock(table));  
command.add(PROPERTIES, getProperties(table));

return command.render();  

}

当用户输入一行create table语句的时候,可查看源码

https://github.com/apache/hive/blob/ff98efa7c6f2b241d8fddd0ac8dc55e817ecb234/ql/src/java/org/apache/hadoop/hive/ql/parse/ParseUtils.java

美团点评 Hive SQL的编译过程

https://tech.meituan.com/2014/02/12/hive-sql-to-mapreduce.html

其中可以看到,建表语句首先会使用antlr4将其转换成一颗语法树

public static ASTNode parse(String command) throws ParseException {
return parse(command, null);
}

然后可以使用getTable抽取其中的库名和表名

https://github.com/apache/hive/blob/f37c5de6c32b9395d1b34fa3c02ed06d1bfbf6eb/ql/src/java/org/apache/hadoop/hive/ql/parse/AnalyzeCommandUtils.java

源码

public static Table getTable(ASTNode tree, BaseSemanticAnalyzer sa) throws SemanticException {
String tableName = ColumnStatsSemanticAnalyzer.getUnescapedName((ASTNode) tree.getChild(0).getChild(0));
String currentDb = SessionState.get().getCurrentDatabase();
String [] names = Utilities.getDbTableName(currentDb, tableName);
return sa.getTable(names[0], names[1], true);
}

https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/parse/ParseDriver.java

public ASTNode parse(String command) throws ParseException {
return parse(command, null);
}

然后比如要提取inputformat，outpurformat，serde和storageHandler

https://github.com/apache/hive/blob/f37c5de6c32b9395d1b34fa3c02ed06d1bfbf6eb/ql/src/java/org/apache/hadoop/hive/ql/parse/StorageFormat.java

源码

要提取字段信息，SkewedValue，表名以及row format

https://github.com/apache/hive/blob/f37c5de6c32b9395d1b34fa3c02ed06d1bfbf6eb/ql/src/java/org/apache/hadoop/hive/ql/parse/BaseSemanticAnalyzer.java

源码

public static List getColumns(
ASTNode ast, boolean lowerCase, TokenRewriteStream tokenRewriteStream,
List primaryKeys, List foreignKeys,
List uniqueConstraints, List notNullConstraints,
List defaultConstraints, List checkConstraints,
Configuration conf) throws SemanticException {
我是源码
}

源码

/**
* Get the unqualified name from a table node.
*
* This method works for table names qualified with their schema (e.g., "db.table")
* and table names without schema qualification. In both cases, it returns
* the table name without the schema.
*
* @param node the table node
* @return the table name without schema qualification
* (i.e., if name is "db.table" or "table", returns "table")
*/
public static String getUnescapedUnqualifiedTableName(ASTNode node) {
assert node.getChildCount() <= 2;

if (node.getChildCount() == 2) {  
  node = (ASTNode) node.getChild(1);  
}

return getUnescapedName(node);  

}

源码

protected void analyzeRowFormat(ASTNode child) throws SemanticException {
child = (ASTNode) child.getChild(0);
int numChildRowFormat = child.getChildCount();
for (int numC = 0; numC < numChildRowFormat; numC++) { ASTNode rowChild = (ASTNode) child.getChild(numC); switch (rowChild.getToken().getType()) { case HiveParser.TOK_TABLEROWFORMATFIELD: fieldDelim = unescapeSQLString(rowChild.getChild(0) .getText()); if (rowChild.getChildCount() >= 2) {
fieldEscape = unescapeSQLString(rowChild
.getChild(1).getText());
}
break;
case HiveParser.TOK_TABLEROWFORMATCOLLITEMS:
collItemDelim = unescapeSQLString(rowChild
.getChild(0).getText());
break;
case HiveParser.TOK_TABLEROWFORMATMAPKEYS:
mapKeyDelim = unescapeSQLString(rowChild.getChild(0)
.getText());
break;
case HiveParser.TOK_TABLEROWFORMATLINES:
lineDelim = unescapeSQLString(rowChild.getChild(0)
.getText());
if (!lineDelim.equals("\n")
&& !lineDelim.equals("10")) {
throw new SemanticException(SemanticAnalyzer.generateErrorMessage(rowChild,
ErrorMsg.LINES_TERMINATED_BY_NON_NEWLINE.getMsg()));
}
break;
case HiveParser.TOK_TABLEROWFORMATNULL:
nullFormat = unescapeSQLString(rowChild.getChild(0)
.getText());
break;
default:
throw new AssertionError("Unkown Token: " + rowChild);
}
}
}
}

分区信息，首先通过取得Map对象，

https://github.com/apache/hive/blob/6f18bbbc2e030ce7d446b2475037203cbd4f860d/ql/src/java/org/apache/hadoop/hive/ql/parse/AnalyzeCommandUtils.java

源码

public static Map getPartKeyValuePairsFromAST(Table tbl, ASTNode tree,
HiveConf hiveConf) throws SemanticException {
ASTNode child = ((ASTNode) tree.getChild(0).getChild(1));
Map partSpec = new HashMap();
if (child != null) {
partSpec = DDLSemanticAnalyzer.getValidatedPartSpec(tbl, child, hiveConf, false);
} //otherwise, it is the case of analyze table T compute statistics for columns;
return partSpec;
}

再转换成List对象

https://github.com/apache/hive/blob/556531182dc989e12fd491d951b353b4df13fd47/ql/src/java/org/apache/hadoop/hive/ql/parse/BaseSemanticAnalyzer.java

源码

public Map partSpec; // has to use LinkedHashMap to enforce order
public List partitions; // involved partitions in TableScanOperator/FileSinkOperator
partitions = db.getPartitions(table, partSpec);

location信息，parsedLocation

https://github.com/apache/hive/blob/0213afb8a31af1f48d009edd41cec9e6c8942354/ql/src/java/org/apache/hadoop/hive/ql/parse/ImportSemanticAnalyzer.java