How was Elasticsearch populated and updated?

Elasticsearch is populated and updated through document indexing and updating operations. Typically, data is sent to Elasticsearch in JSON format via REST API or client libraries.

For indexing (filling), the index or bulk method is used for batch uploads. For updating, the update method can be used, which allows partial modification of a document or re-indexing the entire document.

An example in Go using the official elasticsearch-go client:

import (
    "context"
    "encoding/json"
    "fmt"
    "strings"
    "github.com/elastic/go-elasticsearch/v8"
)

type Document struct {
    Title string `json:"title"`
    Content string `json:"content"`
}

func main() {
    es, _ := elasticsearch.NewDefaultClient()

    doc := Document{Title: "Example", Content: "Document text"}
    data, _ := json.Marshal(doc)

    // Indexing a document
    res, err := es.Index(
        "my-index",
        strings.NewReader(string(data)),
        es.Index.WithDocumentID("1"),
        es.Index.WithRefresh("true"),
    )
    if err != nil {
        fmt.Println("Indexing error:", err)
    }
    defer res.Body.Close()

    // Updating a document (partial)
    updateScript := `{"doc": {"content": "Updated text"}}`
    res, err = es.Update(
        "my-index",
        "1",
        strings.NewReader(updateScript),
        es.Update.WithRefresh("true"),
    )
    if err != nil {
        fmt.Println("Update error:", err)
    }
    defer res.Body.Close()
}

Thus, filling and updating are performed through indexing new documents and updating existing ones via the Elasticsearch API.