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db/Elasticsearch系列/20-Elasticsearch之常见错误

2019-12-30

一 read_only_allow_delete” : “true”

当我们在向某个索引添加一条数据的时候,可能(极少情况)会碰到下面的报错:

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{
"error": {
"root_cause": [
{
"type": "cluster_block_exception",
"reason": "blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];"
}
],
"type": "cluster_block_exception",
"reason": "blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];"
},
"status": 403
}

上述报错是说索引现在的状态是只读模式(read-only),如果查看该索引此时的状态:

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GET z1/_settings
# 结果如下
{
"z1" : {
"settings" : {
"index" : {
"number_of_shards" : "5",
"blocks" : {
"read_only_allow_delete" : "true"
},
"provided_name" : "z1",
"creation_date" : "1556204559161",
"number_of_replicas" : "1",
"uuid" : "3PEevS9xSm-r3tw54p0o9w",
"version" : {
"created" : "6050499"
}
}
}
}
}

可以看到"read_only_allow_delete" : "true",说明此时无法插入数据,当然,我们也可以模拟出来这个错误:

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PUT z1
{
"mappings": {
"doc": {
"properties": {
"title": {
"type":"text"
}
}
}
},
"settings": {
"index.blocks.read_only_allow_delete": true
}
}

PUT z1/doc/1
{
"title": "es真难学"
}

现在我们如果执行插入数据,就会报开始的错误。那么怎么解决呢?

  • 清理磁盘,使占用率低于85%。
  • 手动调整该项,具体参考官网

这里介绍一种,我们将该字段重新设置为:

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PUT z1/_settings
{
"index.blocks.read_only_allow_delete": null
}

现在再查看该索引就正常了,也可以正常的插入数据和查询了。

二 illegal_argument_exception

有时候,在聚合中,我们会发现如下报错:

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{
"error": {
"root_cause": [
{
"type": "illegal_argument_exception",
"reason": "Fielddata is disabled on text fields by default. Set fielddata=true on [age] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory. Alternatively use a keyword field instead."
}
],
"type": "search_phase_execution_exception",
"reason": "all shards failed",
"phase": "query",
"grouped": true,
"failed_shards": [
{
"shard": 0,
"index": "z2",
"node": "NRwiP9PLRFCTJA7w3H9eqA",
"reason": {
"type": "illegal_argument_exception",
"reason": "Fielddata is disabled on text fields by default. Set fielddata=true on [age] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory. Alternatively use a keyword field instead."
}
}
],
"caused_by": {
"type": "illegal_argument_exception",
"reason": "Fielddata is disabled on text fields by default. Set fielddata=true on [age] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory. Alternatively use a keyword field instead.",
"caused_by": {
"type": "illegal_argument_exception",
"reason": "Fielddata is disabled on text fields by default. Set fielddata=true on [age] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory. Alternatively use a keyword field instead."
}
}
},
"status": 400
}

这是怎么回事呢?是因为,聚合查询时,指定字段不能是text类型。比如下列示例:

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PUT z2/doc/1
{
"age":"18"
}
PUT z2/doc/2
{
"age":20
}

GET z2/doc/_search
{
"query": {
"match_all": {}
},
"aggs": {
"my_sum": {
"sum": {
"field": "age"
}
}
}
}

当我们向elasticsearch中,添加一条数据时(此时,如果索引存在则直接新增或者更新文档,不存在则先创建索引),首先检查该age字段的映射类型。如上示例中,我们添加第一篇文档时(z1索引不存在),elasticsearch会自动的创建索引,然后为age字段创建映射关系(es就猜此时age字段的值是什么类型,如果发现是text类型,那么存储该字段的映射类型就是text),此时age字段的值是text类型,所以,第二条插入数据,age的值也是text类型,而不是我们看到的long类型。我们可以查看一下该索引的mappings信息:

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GET z2/_mapping
# mapping信息如下
{
"z2" : {
"mappings" : {
"doc" : {
"properties" : {
"age" : {
"type" : "text",
"fields" : {
"keyword" : {
"type" : "keyword",
"ignore_above" : 256
}
}
}
}
}
}
}
}

上述返回结果发现,age类型是text。而该类型又不支持聚合,所以,就会报错了。解决办法就是:

  • 如果选择动态创建一篇文档,映射关系取决于你添加的第一条文档的各字段都对应什么类型。而不是我们看到的那样,第一次是text,第二次不加引号,就是long类型了不是这样的。
  • 如果嫌弃上面的解决办法麻烦,那就选择手动创建映射关系。首先指定好各字段对应什么类型。后续才不至于出错。

三 Result window is too large

很多时候,我们在查询文档时,一次查询结果很可能会有很多,而elasticsearch一次返回多少条结果,由size参数决定:

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GET e2/doc/_search
{
"size": 100000,
"query": {
"match_all": {}
}
}

而默认是最多范围一万条,那么当我们的请求超过一万条时(比如有十万条),就会报:

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Result window is too large, from + size must be less than or equal to: [10000] but was [100000]. See the scroll api for a more efficient way to request large data sets. This limit can be set by changing the [index.max_result_window] index level setting.

意思是一次请求返回的结果太大,可以另行参考 scroll API或者设置index.max_result_window参数手动调整size的最大默认值:

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# kibana中设置
PUT e2/_settings
{
"index": {
"max_result_window": "100000"
}
}
# Python中设置
from elasticsearch import Elasticsearch
es = Elasticsearch()
es.indices.put_settings(index='e2', body={"index": {"max_result_window": 100000}})

如上例,我们手动调整索引e2size参数最大默认值到十万,这时,一次查询结果只要不超过10万就都会一次返回。
注意,这个设置对于索引essize参数是永久生效的。

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